The Enigma Order

well i built a new comp and was having some major poblems with it, games were crashing after a few mins playing, and i thought it was a driver or GPU problem because 50% of the crashes i managed to alt tab into windows. so when i was about to pack my grafics card to send back, i decided to try to remove 1 of the ram peices, just to see what happend, and crysis seemd to work fine just alittle laggy cause i only had 1gb of ram in the comp atm. then i tried to switch the ram i tok out with the one inside and tested crysis, it seemd to work fine, maybe alittle more lag, but whenever i had the two ram peices inside games yould look perfect for the 1 or 2 mins i was playing them untill it crashed, i didnt get any BSOD's or anything.

so i dont know much about hardwere, so im wondering what the problem is, is the PSU(SP-600A2C), or my mobo(MSI P35 neo) or the ram(cant remeber the name 2x1gb DDR2 Ballistix or something) maybe some of you know anything about shit like this