My first build having problems

[gydra]

My build consists of:
GIGABYTE GA-M61P-S3 Socket AM2 Motherboard
AMD 64 X2 5200+ Processor
mushkin 2GB DDR2 800 RAM
Seagate Barracuda 320 SATA 3.0Gb/s Hard Drive Jumpers set only to 1.5Gb/s
NZXT Precise PRC 650W Power Supply
ASUS SATA DVD Burner
Aerocool ZeroDegree Case

I am somewhat inexperienced at putting together a computer especially mounting the motherboard. Do I use the fiber washers? My case had one mounting standoff missing so the motherboard sort of bends downward if pressure is applied to it. I know that has to be remedied. However, my computer did boot, however, it frequently randomly shuts down. I was able to get XP Proffesional 64-bit installed, but I can't do a lot in windows before it shuts down. It did that during the OS installation when accessing the HDD, although at the time, I thought Windows just didn't recognize the SATA HDD. After it shuts down, I can immediately turn the machine back on, sometimes it shuts off immediately, and sometimes it can be used temporarily. I check to see if it was a cooling problem, and connecting the huge 25 CM side fan seemed to prolong the duration the the system would stay on. However under the bios, the CPU Temp and Case Temp never went above 45 C, although I would imagine that was only the case because windows wasn't running. I noticed though, that after my computer shuts down, the fan on the power supply still runs. Would this be an overheating problem on the power supply's part? The case has stops (feet) on the bottom, and the power supply's fan is located on the bottom and it's vent is a filter that doesn't allow much airflow, also it was placed on tall carpet, which the later will be fixed as well. Is this an accurate diagnosis to my problem, or is it something else? Any help would be greatly appreciated.

[durant0s]

I'm no expert myself but if the motherboard isn't mounted properly thats inviting a whole host of problems.

[LeftyAce]

It could be a couple of things....Follow these instructions to begin troubleshooting: http://forum.pcmech.com/showthread.php?t=132409

[Cricket]

Make sure the CPU heatsink is installed properly. If it's not sitting flat and level on the CPU it's not making full contact and the CPU will overheat.

Do you have access to another compatible power supply? I don't think NZXT power supplies are thought of as good quality units and yours could be defective.

Get the computer case off the carpet.

Cricket