computer randomly reboots

hi i just rebuilt my pc at the end of december i put a 2.4 64 bit amd in it, it has a 1024 megs of ram, 100 gig hard drive, 500 watt power supply,xtasy 9600 ati video card,oh and its a socket939 gigabyte board.so with that said HHEEEELLLLPPP!! its only done it for a couple weeks now and the reboots are so random, its done it about 10 times now id say once i hadnt even been logged in for a minute and it did it i was playin a game once when it happened,too and various other times ive ran mem test on it,and no viruses are found either the transisters on the
mother board look fine. there was some system reboot option in windows i unchecked that cause i read that it could be the cause,WRONG! the funny thing is ill go some days all day and it wont do it so i dunno does anyone have any idea???

 

have you checked for heat problems, especially the cpu.
Maybe try taking the cooler off and reapply some more compound, making sure that it is a very thin even layer not too much as that can be just as bad as too little.
What PSU is it? 500w should be fine, but if its a crap one then it could be causing the problem.

 

You might try checking for newer drivers. Some people suggest that the graphics card driver may be bad or your power supply may be going south. I updated my power supply and updated by graphics card driver. I also unhecked the "reboot after system failure" option in My Computer.

 

How would you update the graphic driver if the PC won't get past the initial boot screen?

 

@ bigdk - the guy never said he couldnt get past the initial boot screen ...

random reboots ay...like big Dk said its possibly a power problem or a heating issue, when your pc is on (and not crashing) download this program called sensors view ( http://www.download.com/SensorsView-Pro/3000-2094_4-10490868.html?tag=lst-0-1 )

see how hot its saying your systems components are and post back here

 

Sorry mixing my threads.
Ignore the last comment, I'll go back to sleep now!!!!!!

 

ok i used sensor view and everything looks normal,ill try updating my video card drivers. after that the omnly other thing i can think of would be to replace the power supply ,and given my recent history with them on this pc and the old socket a mobo i had in it before i suppose it could be it....