I believe is the web address for memtest86+ if not google that name "memtest86+" and it should be the first link.......put that on a bootable CD or floppy and make sure the CD or floppy drive is first in the boot sequence...this program boots before windows and tests your RAM.....if it shows errors (let it run for atleast a couple hours by the way)...anywho if it shows errors then your RAM is fault and causing the problem.
Also use a program like motherboard monitor 5 to check your voltages....
Your +12v , +5v, and +3.3v rails should be right around those values...if your +12v is hitting like 11.5 or below that's a problem...if your +5v is hitting like 4.8 and below thats a problem...if the 3.3 is hitting like 3.15 and below that's a problem, which all of those suggest the PSU is crapping out or was simply a dud from the get go and you should get it replaced. Good luck, let me know what happens.
Good RAM BTW, i got the same brand, XBL series
.........same graphics card as well