need more power?

[Gebo]

so i've been told that maybe the reason my computer randomly reboots may be that my power supply isn't beefy enough. i've never had this problem before but at least the power connection to the board isn't frying. yet. it's just been since my board was repaired. it's a 650 watt ps and i was told to go with 1,000 watts. anyone have any wisdom on this topic they could share with me?

again, it's not a virus or software based problem
i ruled out bad memory (ran 2 seperate non-windows tests)
visual inspection of mobo looks ok

[TheAllusionist]

The newer video card require a lot more power, especially if you are running two SLI, of course now days you might be running two quadcore CPU's, two monitors, six fans and a recirculating liquid cooling system.....................................

I actually had similar problems long ago and when the power supply cooled off the system would fire up, so my question might be is your PS shutting down, obviously it is, although 650 watts isn't bad, why not replace it, they aren't that expensive, especially if you search online. IF nothing else the new bad boy is ready for whatever yo slip in next as far as motherbard/CPU and video cards?