Not knowing too much about your setup, so this may not even be close.

I run an i7 extreme with 3 280GTXs on a corsair 1000 watt. I had random lock ups, and video garbage displayed similar to that screenshot, and after taking some time going through everything, I found that I was crossing rails from the power supply. Once I wired everything properly, all appears to be well. So if your video card requires multiple power inputs, make sure they are on the same rail.