I have 2 NVIDIA GeForce 8800 GTs with the SLI enabled and I have always kind of had some weird problems with my computer but they have become worse over time. Sometimes randomly my computer will just all of a sudden shut off. Sometimes it will start back up again but other times I will keep hitting the power button and it will turn on for a few seconds then turn off right away. Other times it will turn on but it doesn't seem like the video cards are turning on because I just have a blank monitor. It seems the only way I can get it to boot back up again is either by taking off the SLI connector and putting it back on or unplugging one of both of the video cards and replugging them back in. Another thing that I don't know if it has to do with it is if I move my tower even a little bit its enough to make my computer shut down. I am guessing it's video card related. Thanks