Unstable memory clocks/timings, the 180-181.xx drivers from nvidia and unstable graphics card frequencies can cause this issue. Make sure its none of these and run anything at stock to see if it still occurs.
x2 Thermaltake Blue LED 120mm 2800rpm fans, Zalman CNPS 9900
Mouse
Logitech LX310 2.4Ghz Wireless Laser Mouse
Keyboard
Logitech LX310 2.4 Ghz Wireless Keyboard
Internet Speed
32mb Download, 12mb Upload from Comcast
Other Info
300$ custom watercooling setup. Antec 1200 big boy Radiator, Dual bay XPSC reservoir with clear bubble window, OCZ hydropulse 800L/H 12v pump, 12 ft tygon 1/2" ID, 3/4" OD tubing, Feser One UV Green 1 L fluid. (and VID-NX480 waterblock)