hi, i have no idea why my home built computer keeps on restarting. i will try to leave all the necessary information, please ask me if you want any other information to help me figure this out!

motherboard: msi k8n neo nvidia nforce 3 250Gb chipset
ram: mushkin 512mb pc3200 at 400mhz
harddrive: seagate 120gb
power: 350 watt
processor: amd athlon 64 3200+ 754 socket
windows type: windows xp professional with service pack 2
video card: nvidia geforce 6800 agp

yea so, for some reason the computer kept on restarting itself every so often. everything would suddenly just restart, as if i had pressed the restart button. sometimes it would be hours before a restart, other times, just minutes. i checked the CPU temperature after, and its around 40 celcius, i dont know if thats the problem. iif you can, please help, thank you.

That CPU temp is fine, I doubt that is your problem.

Do you have up to date Antivirus protection? Have you checked your system for virii, or spyware recently? Some virii lately will make your machine reboot. You might take a look in the Security forum, and read the following topic:

http://www.daniweb.com/techtalkforums/thread5690.html

Another thing: Have you installed anything new lately? Like new software? Windows XP Service Pack 2? (Read this if you just installed SP2 and started having this problem: http://www.daniweb.com/techtalkforums/thread10031.html).

If you're sure you have current virus protection, and aren't infected with something, or loaded with spyware, you might consider checking all your cards and connectors inside the case, (Video cards, sound cards, modems, memory, hard disk cables, etc), to be sure nothing has worked loose, as that can cause intermittant reboots, especially as the PC heats up and parts expand. (I usually actually remove the cards and hard disk cables from the slots, then reinsert them to insure I'm getting good connections).

Hope some of this helps.

Thanks! I'll check up on all of this soon