check your power supply..
does it just turn off, or do you get the BSOD? Does it try to reboot?
maybe try some different memory?
have you added any new devices lately?
im i reading that right that the ram is set at .7500V???it should be on the DDR3 card at what voltage it should run at i believe.. dont have one in front of me to verify.
board, ram, cpu, psu, etc...
Do you have an extra power supply you can swap?Here's some more info: http://www.techsupportforum.com/forums/f210/power-supply-information-and-selection-192217.html
Another thing you can try before buying the supply is resetting the CMOS.I've had mine get corrupted and cause issues in the past.Other obvious things to check are CPU cooling block secured? Fans all spinning? including cpu and video card?Remove a stick of ram at a time as noted earlier.Is the Mobo bios the latest?Check the motherboard manufacturers site to see if there are any forums or faqs that list the problem.As far as power supply size I'd recommend the highest you can afford. It's sooo often the part that is skimped on and yet is one of the most important.Good Luck
did you say the problem started after a driver update?.....give me a brief description of what you did, when the problem started.