Have you tried uninstalling and re-installing the nvidia driver (update, if you don't have the latest)
Is any part of your computer overclocked?
Are the temps under load ok?
What is your computers specs (please include PSU make and model)?
XFX 780i 3-way SLI
XFX GTX 285 1GB
Thermaltake Toughpower 650w
Intel Core 2 Quad Q6600 @ 2.4GHz overclocked to 2.8GHz
RAM 4GB DDR2 800MHz, overclocked slightly i think.
Driver ver is 182.06. Should i use the driver that is under optional windows updates??