Just a couple of Obvious recomendations
Check the Memory ... Change out or try other known good memory..
Update the Motherboard Bios....
Make sure this machine is NOT overclocked.... I know some will say that you can get away with this, and sometimes you can BUT sometimes you can't, and its NOT worth the trouble it can cause....
Make sure the cooling fan on the CPU heatsink is working properly, and if possible, go into the bios and check the CPU temp to make sure it is within range, and that the fan is working at the right RPM...
Take out ALL the cards except the video card to make sure that there is not a hardware conflict...Then install 1 card at a time to let Windows deal properly with the IRQ assignments.....
Hope this helps
SeeYa