Hi all,

I built a computer a few months ago. Nothing high powered, but a basic desktop. Randomly, infrequently (usually maybe like twice a month), it'll completely freeze such that it won't even allow a soft boot (ctrl alt prt scr does nothing) and requires a hard boot.

I first thought RAM. I did some memtesting and found nothing. I've alternately removed each stick of ram and it happened again. What could this be? Is there a diagnostic I should run? I'm thinking maybe it's the mobo.

Specs:
kubuntu 9.04, up to date
AMD Phenom X3
Gigabyte GA-MA790X-UD4P
OCZ Reaper 2x2gb
EVGA GeForce 9800GT 512mb