I see you did list the timings on your RAM but just in case, go look up your memory manufacturer's recommended timings and make absolutely sure your BIOS settings match what they recommend. Once you have that set up, go get Prime95 (http://mersenne.org/freesoft/default.php) and run the torture test overnight. If it runs all night with no errors, then it is likely not a RAM or base system hardware failure, which would tend to point to the graphics drivers or hardware as the failure point.