random reboots

[northrop]

my computer has been acting up on me recently. few days ago it rebooted once.. then again... and finally, today it rebooted about 10 times already. from what i see, the longer the computer stays on, the more it reboots. at first glance i thought that temps are too high, but SpeedFan returns adequate temps.

system setup:
700Watt Seasonic M12
EVGA 680i mobo
QX6800 (stock) cooled with Arctic Colling Freezer 7 heatsink
2gb Corsair XMS2
nVidia 7900 GS (stock)
320gb WD
2 optical drives
WinXP

temps:
CPU - 36C-40C on idle, up to 55C under load
HD - 25C

i ran memtest for couple hours, and got nothing. also diagnosed my HD, and still nothing. the system has been running flawlessly for well over a year now. so what gives? Nod32 scan returned no viruses. couldn't find anything suspicious with hijackthis.

so what could it be? PSU? or should i just reinstall the OS(haven't done that since the original build), and hope for the best? any ideas?

 

[gaspah]

sounds like a psu but you have a solid psu... it could be anything really a hole in your ram does the same thing. you really need to test parts.. im guessing you have pair of ram (2x1GiB)? boot it with one at a time run your intensive whatever and see if it reboots. to test other parts you're simply going to need other parts..