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Building the Perfect Bleeding-Edge PC, Part 2
Pages: 1, 2, 3, 4, 5, 6

Installing the Motherboard

With the motherboard populated, the next step is to install it in the case. To do so, lower it into place gently, verifying that each motherboard mounting hole has a corresponding standoff installed and that no extra standoffs are present. Align the motherboard rear I/O panel carefully with the I/O template, and slide the motherboard into position. The threaded portion of each brass standoff should be visible through the corresponding motherboard mounting hole, although you may have to apply slight pressure toward the rear of the case to force everything into alignment.

Note: The P160 includes several types of screws, including two types that appear to fit the brass standoffs. In fact, only one of those types has the proper thread--the one with slots for both Phillips and standard screwdrivers. The other type, which requires a Phillips screwdriver, is intended for mounting optical drives and has a finer thread.

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Install two or three screws initially, but don't tighten them completely. Using the available slack, force the other mounting holes into alignment and drive screws into each of them. Once you have screws in each position (11, in the case of the D925XCV), tighten all of them gently. Don't overtorque them, or you may crack the motherboard.

Once the motherboard is secure, connect the front-panel switch and indicator cables, as shown in Figure 13. Do the same for the front-panel FireWire, USB, and audio cables.

Connecting the front-panel cables
Figure 13. Connecting the front-panel cables

As we finished connecting the front-panel cables, we noticed a loose cable with a Molex connector hanging from the inside front of the case. As it turned out, this cable powers the LCD temperature readout on the front of the case. We hadn't intended to use any Molex devices in this system, so we hadn't installed the optional Molex power cable when we assembled the Antec NeoPower 480 power supply. Fortunately, the jacks on the NeoPower 480 are readily accessible after the power supply is installed, so we simply connected the Molex power cable to the power supply, as shown in Figure 14, and connected one of the Molex plugs to power the front-panel display. Since we were working in the vicinity, we connected the power supply fan control header (the blue and black wires in Figure 14) to a fan power header on the motherboard.

Adding a Molex cable to the NeoPower 480
Figure 14. Adding a Molex cable to the NeoPower 480

The next step is to connect the ATX12V main power cable, as shown in Figure 15. The D925XCV motherboard uses the new 24-pin ATX12V connector rather than the traditional 20-pin connector. You can use an older 20-pin ATX12V power supply with this motherboard, but if you do, you should also connect a Molex connector from the power supply to the Molex alternate power connector on the motherboard, visible in Figure 16

Connecting the ATX main power cable
Figure 15. Connecting the ATX12V main power cable

Whatever you do, don't forget to connect the ATX12V CPU power cable, as shown in Figure 16. If you fail to connect this cable, the system won't boot. When the Pentium 4 was first available, we forgot to connect this cable for the first half-dozen or so systems we built. Now, it's so automatic for us to do so, we search frantically for this connector on AMD Athlon XP and other systems that don't use it.

Connecting the ATX12V CPU power cable
Figure 16. Connecting the ATX12V CPU power cable

Prescott-core Pentium 4 processors such as the Pentium 4 560 run very hot, so providing adequate cooling is essential. As Figure 17 shows, the processor in this system is cooled by three large fans--the CPU fan itself, the power supply fan, and a 120mm supplemental case fan. With all of those fan blades spinning, it's important to make sure that no wires can foul the fans. In particular, the CPU fan uses exposed blades and is very vulnerable to becoming entangled with a stray cable.

The placement of the ATX12V CPU power cable makes it very likely to foul the CPU fan unless steps are taken to prevent it. We considered routing that cable down low, near the motherboard, but there wasn't any convenient way to secure the cable in that position. Accordingly, we decided to secure the cable to part of the chassis frame with twist ties, making sure that the cable was routed clear of the CPU fan and the supplemental case fan. We also tucked in the CPU fan power cable, visible near the bottom of the heat sink, to make sure it couldn't foul the CPU fan.

Routing the ATX12V CPU power cable away from fan blades
Figure 17. Routing the ATX12V CPU power cable away from fan blades

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