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Building the Perfect Budget PC, Part 2
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Installing the motherboard

With the motherboard populated, the next step is to install it in the case. To do so, lower it gently into place, verifying one last time that each motherboard mounting hole has a corresponding standoff installed and that no extra standoffs are present. Carefully align the motherboard rear I/O panel 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.

As you slide the motherboard into position, verify that none of the ports on the I/O panel are obstructed by the grounding tabs on the I/O template. Ordinarily it's possible to do this by sliding the motherboard into place with the rear edge tilted slightly downward and the front edge slightly upward. In this case, we found that no matter how we tilted the motherboard, the grounding tab for the Ethernet port protruded into the port opening. We used a small flat-blade screwdriver, as shown in Figure 12, to maintain slight pressure against the grounding tab while we slid the motherboard into place. (In extreme cases, you may need to use pliers to bend a grounding tab out of the way before positioning the motherboard.)

Figure 12
Figure 12. Ensuring the grounding tab clears the Ethernet port

Once you have the board positioned correctly, partially insert two screws to hold it in place. Use gentle pressure to force the motherboard mounting holes into alignment with the brass standoffs, and partially insert the remaining screws. Once all eight screws are aligned and started, tighten all of them finger-tight. To avoid possibly cracking the motherboard, do not apply too much torque to the motherboard mounting screws.

With the motherboard secured, the next step is to connect the front panel switch and indicator cables, as shown in Figure 13. Switch cables are not polarized and may be connected in either orientation. LED cables are polarized and should be connected with the ground wire (usually green or black) to the ground pin and signal wire (usually red or white) to the signal pin.

Figure 13
Figure 13. Connecting the front panel switch and LED cables

The next step is to connect the front panel USB cable. Intel has defined a standard 5X2 USB connector block, with one pin blocked for keying. Each USB port requires four wires: +5VDC (sometimes labeled Power), D- and D+ (the two USB signal wires), and Ground. The Antec SLK2650BQE case provides a front panel USB cable with a 5X2 keyed connector block, and the ASUS A7N8X-VM/400 provides a corresponding set of header pins. After checking the pinouts to verify that both the cable and header pins followed the Intel standard, we connected the front panel USB cable, as shown in Figure 14. Antec offers an optional adapter that converts the front panel USB connector block to individual connectors for those who use a motherboard with nonstandard USB header pins.

Figure 14
Figure 14. Connecting the front panel USB cables

The next step is to connect the ATX main power cable to the motherboard, as shown in Figure 15. Verify that the cable seats completely and that the latch snaps into place. Unlike Intel motherboards, all of which place the main power connector near the right front edge of the motherboard, this ASUS motherboard places the main power connector near the I/O panel at the rear of the motherboard. We dislike this placement, because it requires the unwieldy 20-wire main power cable to cross the motherboard, potentially interfering with the CPU cooling fan and other components. Make sure to route and secure the main power cable carefully to avoid its possibly fouling the CPU fan or rear case fan.

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

The final step is to connect the fan control cable from the power supply to the fan power header located adjacent to the main ATX power connector, as shown in Figure 16. Connecting this cable allows the system BIOS to monitor and control the speed of the power supply fan.

Figure 16
Figure 16. Connecting the fan controller cable

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