Computer Help :D

[Raist]

would need specifics on your hardware to be able to give a more informed answer, but if you are running a multicore processor and the number portion of your video card starts with 4 or higher (ATI/AMD 4000 or nVidia 400 series or higher), chances are you may need a solid PSU over 500 watts. If you only have a 500 or 550, it may be buckling under load depending on your configuration.

Many of the PSU makers have tools to give you a rough idea of what you should shoot for. Here is one from Corsair (been using one of their TX650 80+ models for about 4 years now... solid units, and a really good warranty on them too):
http://www.corsair.com/en-us/psu-finder