installing intel processor socket 775

With Intel's latest processor socket 775 formfactor, Intel has accomplished a couple of noteworthy things. The first was to substantially reduce the complexity and cost of manufacturing its processors; removing the vulnerable and delicate interface pins from the bottom of CPUs meant that manufacturing losses and customer returns both dropped significantly for Intel. The second accomplishment was, unfortunately, to increase the complexity and risk involved in installing one of the new 775 processors into a motherboard.

By removing the pins from each CPU, Intel off loaded the responsibility of adding interface pins to motherboard manufacturers (who also now have to deal with returned merchandise and angry customers with bent socket pins). This is a bad thing for Intel users in general, as now the motherboard is the most likely component to be damaged during an installation gone bad, and compared to Intel many motherboard manufacturers are notoriously unreliable in providing replacement parts.

Here at PCSTATS, we had our share of troubles and frustration with the new installation method before we got completely used to it, so we thought we'd run off a quick guide illustrating the procedure for the benefit of our readers. If you are planning on building a Intel based computer anytime soon, bookmark this article now...!

The LGA 775 processor chip and socket

As you probably know by now, Intel processors have no pins at all. Instead they merely have the electrical contacts where the pins (which are now built into the socket on the motherboard) will touch. While the lack of pins makes these chips much less fragile, the bottom of the processor should not be touched, as the contacts can be damaged.

On the left above is the previous socket 478 style Intel processor, at right the current socket 775 style pinless processor. In all other physical respects the new chips are unremarkable, so let's move on to the socket.

As you can see, the array of pins which connect the processor to the motherboard are now attached to the socket and they are very fragile and easily bent. All socket 775 motherboards feature the metal shim (load plate) pictured above, which serves the dual purpose of locking down the processor once it is installed and protecting the pins from harm when it is not. Most boards also implement a protective plastic cover which fits over the load plate when no processor is present, hiding the pins completely. The lever secures the shim in place, holding the processor when it is installed.

It is extremely important that the processor be installed slowly, carefully and vertically into the socket, and removed the same way. Any careless handling will damage the pins, and may leave you with a useless motherboard.

Now its time to describe exactly how to install one of these chips correctly. It's not the hardest thing in the world, but it pays to be careful and follow a predetermined set of steps.

Installing Pentium 4 Processor in the 478-pin

The Boxed Pentium 4 Processor in the 478-pin Package
Processor Overview
The Intel Pentium 4 processor is based on the Intel® NetBurst™ micro-architecture and includes several new performance enhancing features.

• Hyper-Threading Technology
  The Pentium 4 processor supporting Hyper-Threading Technology ^†increases processor efficiency by executing more than one instruction thread at a time. This technology is designed to deliver superior performance with multi-threaded applications and in multi-tasking environments.
• Hyper Pipelined Technology
  A deeper pipeline enables instructions inside the processor to be queued and executed at a much faster rate, and allows the Pentium 4 processor to achieve the world's highest clock speeds for desktop PCs.
  
• Streaming SIMD Extensions 2
  Streaming SIMD Extensions 2 consists of 144 new instructions including SIMD double precision floating point, SIMD 128-bit integer, and new cache and memory management instructions. Streaming SIMD Extensions 2 enhances performance to accelerate video, speech, encryption, imaging, and the most demanding of Internet computing, and non-threaded workstation applications.
• Streaming SIMD Extensions 3
  Streaming SIMD Extensions 3 consists of 13 new instructions including 5 Complex Arithmetic evaluations, 2 Improved Load/Stores for improved performance, 4 Horizontal evaluations to improve speed of evaluations, and 2 Improved Hyper Threading instructions.
• 800-MHz/533-MHz/400-MHz Intel® NetBurst™ Micro-Architecture System Bus
  Multiple system bus transfer rates that help speed the transfer of information from the processor to the rest of the system, improving throughput and performance. Also provides the user with the flexibility to take advantage of higher system memory bandwidth.
  
• Advanced Dynamic Execution
  Extends the Dynamic Execution features found in the previous generation P6 micro-architecture. Improved branch prediction accelerates the flow of work to the processor and helps overcome the deeper pipeline. Very deep out-of-order speculative execution carries out over 100 instructions speculatively, ensuring that the processor's superscalar execution units remain busy, improving overall execution.
  
• Enhanced Floating Point/Multimedia Unit
  A 128-bit floating-point port and a second port for data movement enable smooth lifelike 3D and graphics.
  
• Execution Trace Cache
  Advanced L1 instruction cache removes decoder pipeline latency, and caches "decoded" instructions, thus improving efficiency and hit rate to cached instructions. The 12 Kµop portion of the L1 cache supplies decoded instructions into the processor pipeline. There is also an 8 KB data portion of L1 cache.
  
• Rapid Execution Engine
  Integer Arithmetic Logic Unit (ALU) clocked at twice the core frequency provides four ALUs of computing bandwidth and allows lower latency execution increasing performance for certain integer operations.
  

The Intel NetBurst micro-architecture enables the Pentium 4 processor to achieve breakthrough performance for visual computing, concurrent application environments, and the future of the Internet.


Included with the Boxed Pentium 4 processor in the 478-pin Package

• Intel Pentium 4 processor in the 478-pin package
• Intel Designed Thermal Solution (includes high quality variable speed fan heatsink and clip assembly)
• Thermal interface material (attached to the heatsink or thermal grease applied with applicator)
• Installation Instructions and Certificate of Authenticity
• Intel® Inside logo label

The Pentium 4 processor in the 478-pin package refers to Pentium 4 processors in the 478-pin Flip-Chip Pin Grid Array (FC-PGA2) package with an Integrated Heat Spreader (IHS) that aids in heat dissipation to a properly attached fan heatsink.



Figures 1 and 2: Pentium® 4 processor 478-pin FC-PGA2 Package

The boxed processor fan heatsink uses a variable speed fan that increases in speed (and noise level) as the air temperature entering the fan increases. The fan operates at a set speed until the inlet air temperature (or the air temperature entering the fan heatsink) exceeds the lower set point (see Table 1). The fan speed will continue to increase linearly until the inlet air temperature reaches the higher set point (see Table 1). At temperatures above the higher set point, the fan will operate at its highest speed and noise level.

System integrators should design systems that ensure that the air temperature around the boxed processor fan heatsink (or internal chassis temperature) is kept below the lower set point, for the lowest fan speed and noise level. System integrators must never allow the inlet air temperature to exceed the higher set point. The recommended maximum internal chassis temperature for systems based on the boxed Intel Pentium 4 processor 2.80 GHz (and below) is 40°C. For systems based on the boxed Intel Pentium 4 processor 3 GHz (and above), the recommended maximum internal chassis temperature is 38°C. (Note: Set points vary on boxed fan heatsinks due to processor technology.)

Selecting the correct chassis and verifying proper thermal management is critical for integrating a high quality boxed Intel Pentium 4 processor-based system (see Thermal Management for Systems based on Boxed Pentium 4 processors in the 478-pin Package for information about thermal management considerations and the Pentium 4 processor Datasheet for details on the Thermal Monitor feature). Figure 2 shows the various internal chassis temperatures and the specific impact on the system noise and performance.


Table 1. Boxed Processor Variable Fan Heatsink Set Points

For Boxed Intel® Pentium® 4 Processors 2.80 GHz (and below): Internal Chassis Temperature (°C) Boxed Processor Fan Heatsink Set Points X < = 331 Lower Set Point: Fan speed constant at lowest fan speed. Recommended temperature for nominal operating environment. Y = 40 Recommended maximum internal chassis temperature for boxed Intel Pentium 4 processor-based systems. Z > = 431 Higher Set Point: Fan speed constant at highest fan speed. For Boxed Intel® Pentium® 4 Processors 3 GHz (and above): Internal Chassis Temperature (°C) Boxed Processor Fan Heatsink Set Points X < = 321 Lower Set Point: Fan speed constant at lowest fan speed. Recommended temperature for nominal operating environment. Y = 38 Recommended maximum internal chassis temperature for boxed Intel Pentium 4 processor-based systems. Z > = 401 Higher Set Point: Fan speed constant at highest fan speed

¹ Set point variance is approximately ±1°C from fan heatsink to fan heatsink.

Figure 2. Internal Chassis Temperature Affect On Boxed Processor Variable Speed Fan Heatsink Noise



Identifying a Boxed Processor
Boxed processor test specifications (or S-Specs) marked on the integrated heat spreader of the Pentium 4 processor identify specific information about the processor. Using the S-Spec Reference Table and the information marked on the processor, a system integrator can verify the appropriate speed rating, stepping, lot number, serial number and other important information about the processor. The numbers marked on the processor should match the numbers on the processor box label (see Figure 3).

Once the boxed processor is installed into a system, the fan heatsink covers the integrated heat spreader and all the markings on the processor. The sticker on the box of the boxed processor (that has the processor speed information, test specification, and lot number) can be removed and placed on the inside of the system chassis that the processor is installed into (see Figure 4). This will allow quick access to the information that is no longer available on the top of the processor when the heatsink is installed. If a system's processor is later upgraded or replaced causing the sticker inside the chassis to have incorrect information, the sticker should be replaced, removed or visibly marked as obsolete to avoid confusion.



Figure 3. Processor Box Label



Figure 4. Remove Processor Box Label and Place Inside System Chassis

Platform Component Selection

Motherboard Selection
Also, the Pentium 4 processor in the 478-pin package must be used in a motherboard with a 478-pin micro PGA (mPGA478B) socket. It is important to verify that the specific motherboard model and revision support the specific Pentium 4 processor speed being used. A BIOS upgrade may be required in order to properly recognize and initialize the latest stepping of the Pentium 4 processor. Motherboards must meet the electrical and mechanical specifications of the Pentium 4 processor, as documented in the Datasheet.

Motherboard Compatibility for Pentium 4 Processors Supporting Hyper-Threading Technology:
For additional information on integrating systems based on the Pentium 4 processor supporting Hyper-Threading Technology, refer to the Integration Overview for Systems Based on the Intel Pentium 4 Processor Supporting Hyper-Threading Technology.

Motherboard Support for Pentium 4 Processors with 533-MHz or 800-MHz System Bus:
Ensure that you are using a motherboard that supports the 533-MHz or 800-MHz system bus respectively. Failure to use an appropriate motherboard may result in unstable system operation as well as performance degradation and may result in running your processor out of specification, which will void your processor warranty. Consult your motherboard manufacturer for compatibility

Motherboards that support the Pentium 4 processor and are based on the ATX form factor specification utilize power supplies that follow the ATX12V power supply design guide. Similarly, microATX form factor motherboards that support the Pentium 4 processor utilize power supplies that follow the ATX12V or SFX12V power supply design guides. Both the ATX12V and SFX12V power supply design guides are available on the the Form Factors website ^†.

^† This link will take you off of the Intel Web site. Intel does not control the content of the destination Web Site.

Motherboards intended for system integrators will include the processor retention mechanism (Figure 5). Four holes located around the processor socket allow the retention mechanism to attach to the motherboard. System integrators should follow motherboard installation documentation when installing the processor retention mechanism on the motherboard and integrating the motherboard into a chassis. General installation procedures are described in Integrating Systems Based on Intel Pentium 4 processors in the 478-pin Package.


Figure 5. Retention Mechanism Included with Motherboards



Fan Heatsink Support
The boxed processor includes a high quality unattached fan heatsink specifically designed to provide sufficient cooling to the Pentium 4 processor when used in a suitable chassis environment. The fan power cable must be connected to the motherboard power header as shown in the processor installation notes (included in the boxed processor package).

The motherboard 3-pin header uses two pins to supply +12V (power) and GND (ground). The fan uses the third pin to transmit fan-speed information to motherboards that support fan-speed detection. The motherboard must have a 3-pin fan power header located close to the socket.
Note: Refer to your motherboard manual for the location of the power header.


Chassis Selection
Systems based on the Pentium 4 processor in the 478-pin package must use chassis that comply with the ATX specification (revision 2.01 or later) or microATX specification (revision 1.0 or later), depending on the motherboard form factor. Intel recommends system integrators using ATX form factor motherboards to choose a chassis that complies with the ATX specification (revision 2.01 or later). Likewise, system integrators using microATX form factor motherboards should choose a chassis that complies with the microATX specification (1.0 or later).

The chassis must also support a lower internal ambient temperature than many standard ATX and microATX desktop chassis. The internal chassis temperature for systems based on Pentium 4 processors 2.80 GHz (and below) should be maintained at 40°C (or lower) for chassis in the maximum expected external ambient (which is typically 35°C). The internal chassis temperature for systems based on Pentium 4 processors 3 GHz (and above) should be maintained at 38°C (or lower) for chassis in the maximum expected external ambient (which is typically 35°C). Most chassis designed for the Pentium 4 Processor use extra internal chassis fans to improve airflow. Intel tests chassis with the boxed Intel Pentium 4 Processor and the Intel® Desktop Boards for minimum thermal requirements. The tested chassis list can be located at http://www.intel.com/go/chassis. These chassis meet Intel's processor specifications with the Intel Desktop Boards. It is strongly recommended that system integrators perform thermal testing on the chassis selected for each configuration of Pentium 4 processor-based systems, even when using a chassis on the tested chassis list.

Chassis that ship with installed power supplies must support either the ATX12V or SFX12V design guidelines.



Power Supply Selection
Power supplies must comply with either the ATX12V or SFX12V design guidelines (see the Form Factors website ^†for details) and supply additional current on the 12V power rail through a new 2x2 connector. Also, additional 3.3V and 5V current is supplied through a separate 1x6 connector, on the ATX12V power supplies (SFX12V power supplies do not have the separate 1x6 connector). All Pentium 4 processor-based systems require the standard 2x10, 20-pin ATX power connector as well as the 2x2, 4-pin 12V connector. Most ATX form factor-based motherboards with fully loaded system configurations may also require the 1x6, 6-pin connector. Consult the motherboard documentation to determine power supply requirements.

^† This link will take you off of the Intel Web site. Intel does not control the content of the destination Web Site.

Integrating Systems Based on Pentium 4 processors in the 478-pin Package
Motherboards supporting the boxed Pentium 4 processor include a manual with installation instructions. Consult this manual in addition to the boxed processor manual before building a Pentium 4 processor-based system. In addition, the following information can aid system integrators in successfully integrating a system based on the boxed Pentium 4 processor in the 478-pin package.

Note: When integrating a Pentium 4 processor-based system, be sure to take the proper electrostatic discharge (ESD) precautions. Consider using ground straps, gloves, ESD mats, or other protective measures to avoid damaging the processor and other electrical components in the system.

Motherboard and Retention Mechanism Installation
Once the motherboard has been installed in the chassis, install the retention mechanism (provided by the motherboard manufacturer) to the motherboard. As a supplement to the motherboard manufacturer's installation instructions, use the following instructions for installing the retention mechanism:

1. Remove the four white pushpins (A in Figure 6) from the retention mechanism, if installed (Figure 7). The four black fasteners (B in Figure 6) should remain fully seated in the retention mechanism as shown in Figure 8.
2. Place the retention mechanism on the motherboard, aligning it with the four holes located adjacent to the processor socket (Figure 9). Note that the retention mechanism is symmetrical.
3. Secure the retention mechanism to the motherboard by gently pressing down on the black fasteners into the four motherboard holes, until they snap into place (Figure 10).
4. Insert all four of the white pushpins in the black fasteners. Complete the retention mechanism installation by pushing all four of the white pushpins fully into each of the black fasteners (Figure 11).
5. Gently lift up on the retention mechanism to ensure the base (black fasteners with white pushpins installed) is secured to the motherboard.

Figure 6. White Pushpins (A) and Black Fasteners (B)	Figure 7. Remove White Pushpins from Retention Mechanism	Figure 8. Black Fastener Fully Seated in Retention Mechanism
Figure 9. Align Retention Mechanism to Motherboard Holes	Figure 10. Gently Pressing Down on Black Fasteners into Motherboard Holes	Figure 11. Push Down on White Pushpins to Complete Installation

Processor Installation
As a supplement to the manual provided with the boxed processor, install the processor and fan heatsink in the following manner. Open the processor socket handle (see Figure 12) and carefully align the processor using the pin one markings on the processor and socket for reference (Be careful not to bend any of the processor pins.). The processor pin one marking on the substrate of the FC-PGA2 package should be aligned with pin one mark on the socket (Figure 13). Insert the processor into the socket and close the socket handle.

Figure 12. Open Socket Handle	Figure 13. Align Pin One on Processor to Pin One on Socket

Use the following instructions for installing the fan heatsink:

1. The boxed Intel Pentium 4 processor will have thermal interface material attached to the bottom of the heatsink shown in Figure 15 (Be careful not to damage the thermal interface material.) or included in an applicator (Figure 15). If included in an applicator with the boxed processor, apply all of the thermal interface material to the center of the processor's integrated heat spreader (see Figure 15).
   
   
2. Align the fan heatsink and clip assembly (A in Figure 14) with the retention mechanism (the fan heatsink is symmetrical) and place it on the processor (as shown in Figure 15). Allow the heatsink base to compress (without rotating or twisting) the thermal interface material over the surface of the processor's integrated heat spreader.
   
   
3. With the clip levers (C in Figure 14) in the upward position, push down on all four clip frame corners (D in Figure 14) to secure the clip frame latches (E in Figure 14) to the retention mechanism hooks (F in Figure 14), as shown in Figure 16.
   Note: Make sure the processor fan cable is free from any obstruction and is not trapped under clip frame (B in Figure 14).
   
   
4. Note: It is important to not allow the heatsink to rotate or twist on the processor's integrated heat spreader. Securing the fan heatsink while closing the clip levers will ensure the thermal interface material is not damaged and the processor will operate correctly. Follow these steps, for closing the clip levers and ensuring the thermal interface material is not damaged:
   1. Make sure to close the clips levers in opposing directions, one at a time (levers require force to be completely closed), as shown in Figure 17a. First, close the clip lever (1 in Figure 17b), while holding the topside of the fan heatsink with your other hand (A in Figure 17b).
   2. Then, close the clip lever (2 in Figure 17c), while holding the topside of the fan heatsink with your other hand (B in Figure 17c).
   
   
5. Once the clip levers are closed, verify that the heatsink is securely retained and that the clip frame latches are properly engaged with the retention mechanism hooks.
   
   Note: When installed, the fan heatsink and clip assembly may cause the motherboard to slightly bend or flex. This provides the proper mechanical support for the processor (with attached fan heatsink and clip assembly) and helps prevent against damage during system shipment.
   
   
6. Lastly, connect the processor fan cable to the motherboard fan power header (Figure 18). Consult the motherboard manual to determine the correct fan header to use.
   

Figure 14. Fan Heatsink and Clip Assembly Terminology

Figure 15. Align Fan Heatsink and Clip Assembly	Figure 16. Push Down Clip Frame Corners to Secure to Retention Mechanism Hooks
Figure 17a. Close Clip Levers, One at a Time	Figure 17b. Close Clip Lever (1), While Holding the Topside of Fan Heatsink (A)
Figure 17c. Close Clip Lever (2), While Holding the Topside of Fan Heatsink (B)	Figure 18. Connect Fan Cable to Motherboard

Maintaining and Upgrading Systems Based on the Pentium 4 processor in the 478-pin Package

Processor Removal
Every time the heatsink is removed from the processor, it is critical that the thermal interface material be replaced, in order to ensure proper thermal transfer to the boxed processor fan heatsink.

Note: Be sure to take the proper electrostatic discharge (ESD) precautions (ground straps, gloves, ESD mats, or other protective measures) to avoid damaging the processor and other electrical components in the system.

Caution: If you find that considerable force is required to remove the boxed processor assembly, consider wearing gloves to protect your hands and take care to keep your hands away from any metal edges on the chassis when removing components. Thermal Interface Material Attached to the Heatsink Intel does not recommend the removal of the thermal interface material located on the bottom of the boxed processor fan heatsink. Removal of this material may cause damage to the processor and will void the boxed processor warranty. If you must remove and re-use the fan heatsink, it will require replacement. Also, if the thermal interface material is at all damaged, you must also replace the fan heatsink. Contact Intel Customer Support to receive a replacement fan heatsink. Thermal Interface Material in an Applicator Using the boxed processor without properly applying the included thermal interface material may cause damage to the processor and will void the boxed processor warranty. If you must remove and re-use the fan heatsink, a new application of thermal interface material is required. Contact Intel Customer Support to receive additional thermal interface material in an applicator.

Follow these steps to remove the boxed processor from the system:

1. Turn off the system, unplug and remove the power cable from the system.
   
   
2. Make the processor area accessible and unplug the processor fan heatsink power cable from the motherboard connector.
   
   
3. Open the clip levers (C in Figure 14), one at a time, in opposing directions. Place the clip levers in the upward position (as shown in Figure 19).
   
   
4. Use a #1, small flathead screwdriver to unhook the clip frame latches (E in Figure 14) from the retention mechanism hooks (F in Figure 14). Steps (5) through (7), will describe the method for unhooking the clip frame latches from the retention mechanism hooks. Note: Be careful not to damage the motherboard, when using the screwdriver.
   
   
5. Starting from 1 in Figure 19, from the topside of the clip frame (B in Figure 14), insert the screwdriver in the small notch near the clip frame corner (D in Figure 14), as shown in Figure 20.
   
   Note: The screwdriver must be positioned carefully between the clip frame and the retention mechanism hook (side view shown in Figure 21). Once in place, the screwdriver must be sitting on top of the clip frame latch.
   
   
6. Push down on the clip frame latch and simultaneously rotate the screwdriver towards the fan heatsink, to unhook the clip frame latch from the retention mechanism hook (side view shown in Figure 22).
   
   
7. Repeat steps (5) through (7) for each clip frame latch until all clip frame latches are no longer attached to the retention mechanism hooks.
   
   Note: Be aware that the clip frame latches may re-attach to the retention mechanism hooks. To prevent this, follow these steps:
   
   
   1. First, unhook the clip frame latches on the same side of the fan heatsink (1 and 2 in Figure 19).
   2. Once 1 and 2 in Figure 19 are unhooked, use your free hand to hold the top of one of the clip frame corners (1 in Figure 19), pulling the clip frame slightly upward (prevents the clip frame latches from re-attaching). Then, unhook the clip frame latch on the other side of the fan heatsink (3 in Figure 19).
   3. Now, switch and hold the top of the other clip frame corner (2 in Figure 19) with your free hand, pulling the clip frame slightly upward (prevents the clip frame latches from re-attaching). Then, unhook the clip frame latch on the other side of the fan heatsink (4 in Figure 19).
   
   
8. After all the clip frame latches are unhooked from the retention mechanism hooks, slowly remove the fan heatsink from the processor and retention mechanism. Slightly twisting the heatsink back and forth in the retention mechanism may make the heatsink easier to remove by lessening the surface tension force of thermal interface material between the processor and heatsink.
   
   
9. Once the heatsink is removed, lift the processor socket handle to release the processor pins from the socket. Carefully lift the processor out of the socket (being careful not to bend any of the processor pins).

Figure 19. Sequence for Unhooking Clip Frame Latches	Figure 20. Insert Screwdriver From Topside of Clip Frame, Near Clip Frame Corner
Figure 21. (Side View) Position Screwdriver Between the Retention Mechanism Hook and Clip Frame, While Resting on Clip Frame Latch	Figure 22. (Side View) Push Down on Clip Frame Latch and Rotate Screwdriver Towards Fan Heatsink, to Unhook Clip Frame Latch From Retention Mechanism Hook

Software and Operating System Considerations
The Pentium 4 processor is a completely different micro-architecture from Intel's prior microprocessors that were based on the P6 micro-architecture. The Intel NetBurst micro-architecture supports the entire IA32 instruction set including Intel's MMX™ technology and the Streaming SIMD (Single Instruction Multiple Data) Extension. It also includes 144 more instructions called the Streaming SIMD Extensions 2 or SSE2. The SSE2 instructions complement MMX technology and SSE instructions by supplying increased computation capability support for larger data types (e.g. double-precision floating point numbers and 64-bit packed integer numbers), and several data handling and conversion instructions. In addition, the Intel NetBurst micro-architecture enhances the P6 micro-architecture's floating-point unit.

The Pentium 4 processor supporting Hyper-Threading Technology makes a single physical processor appear as two logical processors; the physical execution resources are shared and the architecture state (which tracks the flow of a program or thread) is duplicated for the two logical processors. For additional information on integrating systems based on the Pentium 4 processor supporting Hyper-Threading Technology, refer to the Integration Overview for Systems Based on the Intel Pentium 4 Processor Supporting Hyper-Threading Technology.

Operating System Support
Nearly all modern operating systems designed for the Intel Architecture have support for the Pentium 4 processor, although some may require specific versions or processor support files. Many Microsoft operating systems like Windows* 98 SE, Windows NT* 4 with Service Pack 5, Windows* 2000, Windows* ME, and Windows* XP support the Pentium 4 processor. Linux* distributions based on the Linux* 2.4 core support the processor. Also, many other vendors have support for the Pentium 4 Processor in their operating systems. System integrators should verify that the operating system they have selected supports the Pentium 4 processor.

Note: Windows XP or certain versions of Linux are required for Hyper-Threading Technology2 support for the Pentium 4 processor. For additional information on integrating systems based on the Pentium 4 processor supporting Hyper-Threading Technology, refer to the Integration Overview for Systems Based on the Intel Pentium 4 Processor Supporting Hyper-Threading Technology.

All operating systems that support the SSE instructions that were first introduced with the Intel® Pentium III processor will also support the SSE2 instructions introduced with the Pentium 4 processor. To experience the power of the SSE2 instructions, it is critical that system integrators install drivers and software that have been optimized for the Pentium 4 processor's SSE2 instructions. For example, for maximum system performance, system integrators using Microsoft operating systems that support DirectX* should load DirectX 8 (or higher).

Software Optimization
With specific drivers that use the SSE2 instructions, graphics accelerators, audio hardware and software, and other system resources can experience substantial performance gain. It is critical that systems also use APIs that use SSE2 instructions to achieve maximum performance. Two examples are Microsoft's DirectX 8 (or higher) and Open GL 1.2 (or higher). Most major graphics accelerator vendors have optimized drivers that use the SSE2 instructions. Graphics card vendors typically highlight support changes with new driver releases. Download and install the latest drivers (dated later than October 2000) from the vendor's Web site. Also, verify that the driver version contains optimization for the Pentium 4 processor.

Many applications also use the SSE2 instructions to experience the breakthrough performance of the Pentium 4 processor. System integrators should contact software vendors to verify support and determine version information.

System performance is greatly affected by proper operating system and driver installation processes. For example, it is important to install the latest Intel® Chipset Software Installation Utility immediately after installing most Microsoft operating systems to ensure proper drivers for the chipset are installed prior to installation of other drivers. System integrators should confirm boxed Intel Pentium 4 processor-based systems are optimally configured and integrated.

Conclusion
Boxed Intel Pentium 4 processor-based systems require proper integration. System integrators that follow the guidelines in this document will experience higher customer satisfaction by providing higher quality systems.

Motherboard Power Connectors

One of the most important connections in the PC is that between the power supply and the motherboard. It is through this connection (or set of connections) that the various voltages and other signals are sent between these two important devices. (You may want to familiarize yourself with these signals in the section on power supply functions if necessary.) Different form factors use different numbers, types, shapes and sizes of connectors between the power supply and motherboard.

Before we look at the connectors, let's talk a bit about the wires that run between the power supply and the connectors themselves. Pretty much all wires within the PC are made from copper, due to its excellent conductivity, relative low expense, and flexibility. The most important characteristic of a wire is its size, and more specifically, its cross-sectional area. The reason is that the resistance of the wire is inversely proportional to the cross-sectional area of the wire. Thicker wires can carry more current, while the higher resistance of small wires causes heating when they are subjected to a high current, which can be hazardous. Since some wires need to carry more power than others, they are given different thicknesses. In addition, most motherboard connectors have multiple wires for the main voltage levels. This allows for more current, spread out between the different wires.

In the electronics world one standard used for wire thicknesses is American Wire Gauge, or AWG for short. The smaller the AWG number, the larger the wire. These numbers go from 0 (below 0 actually) to 50 and above, but for electronics the most common gauges are between 8 and 24. For motherboard connectors the wires are usually AWG 16, 18, 20 or 22. The table below shows these four sizes and some relevant statistics. You'll notice that the numbers are not linear with the actual size of the wire; AWG 16 wire is almost four times the cross-sectional area of AWG 22 wire.

AWG	Diameter (mm)	Cross-sectional area (mm²)	Approximate Maximum Current (A)	Relative Size
16	1.29	1.31	19
18	1.02	0.82	15
20	0.81	0.52	10
22	0.644	0.33	8

Note: The relative sizes of the four wires shown above (and below) are to scale--meaning that their relative sizes are accurate, but all four are of course enlarged. Also, the current capacities above are approximate maximums and probably not what would be considered safe or reasonable to use in a responsible design.

The other issue of interest to us regarding wires is the color of their insulation. There are standards established for the colors of various wires, to help avoid confusion by those who work with different components and PCs. While not all manufacturers follow these conventions, most do. If they do not, problems can easily occur when a technician sees a black wire, assumes it is a ground (which it usually would be) and then finds out the hard way that it is not.

Below are diagrams that show the configuration of pins for the various connectors used by different form factors between the power supply and motherboard. In each diagram the pins on the power supply connector are shown in their correct orientation. The color of each pin is the color of the wire established as a standard for that pin. Outside the rectangular outline of each connector, next to each pin, is a depiction of the recommended AWG size for the wire going to that pin, and the name of its signal or voltage. Note that the diagrams are not to scale. Note also that they are shown from the perspective of the connector coming from the power supply. For those connectors with two columns of pins, the mating motherboard connector will have its pins in a mirror-image configuration.

Alright, enough with the preamble. Let's look at the connectors, starting with the oldest style. The PC/XT, AT, Baby AT and LPX form factors all use the same pair of 6-wire connectors, usually called "AT Style" connectors. They are typically labeled either "P8" and "P9" (what IBM originally labeled them) or "P1" and "P2". (Actually, the PC/XT form factor omits the +5 V signal on pin #2 of P8, but otherwise is the same.)

The two "AT style" power connectors, P8 (left) and P9. On the PC/XT, pin #2 of P8 is left unconnected.

The biggest problem with the design IBM used for these power connectors is simply the fact that there are two of them and they are the same size and shape. The connectors are physically keyed so they cannot be inserted backwards, but it is very possible to accidentally swap them. If you do this, you will be putting ground wires where the motherboard expects live power and vice-versa, and the results would be catastrophic. Thus, technicians working with older systems developed the well-known mantra: "black wires together in the middle"! :^)

Proper installation of the two AT-style power connectors to a motherboard. Notice the four black wires together in the middle. Incidentally, in this picture the connectors are shown upside-down from the diagrams above; pin #1 of P8 is at the bottom, pin #6 of P9 at the top. In the background is an ATX-style motherboard connector; this board can work with either form factor of power supply. (I don't know what the wire gauge standard is for the AT connector wires; if somebody out there does, please let me know.)

Original image © Kamco Services Image used with permission.

Starting with the ATX/NLX power supply, Intel did away with the potential P8/P9 risk by making the main connection a single piece, and using only dissimilar shapes on any other connections between the power supply and motherboard. These are called "ATX Style" connectors. For its regular power supply connection, ATX uses a 20-pin connector with a square hole for pin #1 and round holes for the other 19 pins.

The main ATX/NLX power connector. The wires are AWG 18, except for the curious pin #11. There, the specification calls for two AWG 22 wires in the same pin, a +3.3 V signal (orange) and the default +3.3 V sense signal (brown). If the optional ATX connector (below) is used, the +3.3 V sense signal here can be omitted and a regular +3.3 V line put into pin #11. Note that the connector has 20 pins, but 21 wires.

In addition, the ATX specification (version 2.03 is the latest) defines an auxiliary 6-wire connector (in a 1x6 configuration) and an optional 6-wire connector (in a 2x3 configuration). The auxiliary is intended for motherboards that require a lot of power to run their components (250 W or more); it consists simply of more, thicker (AWG 16) wires for the +3.3 V and +5 V signals. The optional connector carries additional signals, as described here.

The ATX auxiliary (left) and optional connectors. The auxiliary connector wires are AWG 16. The five wires on the optional connector are AWG 22. FanM is plain white, FanC is white with a blue stripe, +3.3 V Sense is white with a brown stripe, 1394R is white with a black stripe, and 1394V is white with a red stripe.

The SFX power supply uses a main connector very similar to that of the ATX. The only difference is that pin #18 is omitted, since the SFX specification does not call for a -5 V signal. The SFX optional connector is similar to the ATX one but stripped down; only the Fan ON/OFF signal is provided, on pin #2. There is no auxiliary connector for the SFX supply, which is not intended for use in systems requiring a lot of power.

SFX main and optional connectors. The main connector wires are AWG 18 except for the pin #11 combination, each of which are AWG 22. The lone wire on the optional connector is also AWG 22.

Finally, the WTX form factor. Since WTX is a design intended for workstations and other high end systems, it has a large number of connections to carry the tremendous amount of current that WTX supplies are capable of providing. WTX power supplies therefore have a completely different motherboard interface. The two primary connectors are the 24-pin "main" connector ("P1") and 22-pin "additional" connector ("P2"). Despite P2's name, it is really required by the design, since all the control signals are on it.

WTX main (left) and additional connectors, P1 and P2. The main connector's wires are AWG 18 except for the two low-power standby signals, which are AWG 20. Similarly, the additional connector uses AWG 18 for the 12V and ground power lines, and AWG 22 for the signals and sense lines.

But wait, 40 lines isn't enough; we're not done with WTX yet. :^) In addition to the above, three more connectors are defined. P3 is an eight-pin optional connector (with six pins used) that provides +12 V power to optional power modules or DC-to-DC converters used for additional processors and/or memory within the system. P4 and P5 are six-pin optional connectors used in a similar fashion, to provide additional current for multiple-CPU motherboards or other applications. (Some +12 V power is also provided on P2.) The spec seems to be intentionally flexible (read: vague) regarding how these connectors are to be used.

WTX optional connectors; P3 (left) and P4/P5. Note that unlike other connectors, the wire color standard for these +12 V signals is white, not yellow. All wires are AWG 18.

Note: In addition to the connectors described above, the newer form factors that use soft power also have a connection from the power switch on the case, back to the motherboard.

How to Set Jumpers

Jumpers and Dip switches are used on motherboards to configure settings according to information that is supplied in the motherboard's user manual.

Close-up views of a block of jumpers ( above left) and two blocks of DIP switches ( above right) found on most motherboards.

Below is an image of an individual jumper showing its top and bottom. The wire crosses over the top. The jumper must be fitted so that the flat bottom makes connection with the surface of the motherboard, as shown in item 2.7 below.

A jumper can cover two metal pins. Two uncovered metal pins can clearly be seen protruding vertically from the surface of the motherboard in the image of a block of jumpers on the left.

When a jumper fits over two pins, it shorts a connection and enables an option - as illustrated and explained in the motherboard's user manual. All of the major motherboard manufacturer's make user manuals availableas downloads, usually in the PDF format.

MSI provides excellent user manuals in the PDF format. and look under the motherboards or mainboards products. At the time of writing (December 2006), the motherboards will be shown as Socket LGA775 for Intel processors, or Socket AM2 for AMD processors.

If a jumper is left hanging on one pin, or two pins are left unjumpered, the option is left open and is therefore not enabled.

DIP switch settings have On and Off switches that operate in the same way as a light switch. The On position is marked. The Off position is usually the opposite of the On position. You should use a screwdriver with a small head, or a pair of tweasers to move the switch into the On or Off postition.