First off, I hope this is the right forum to be posting in; my apologies if it isn't. So a couple of times in the last month or so my computer has crashed whilst gaming (the display went all weird - random colours, pixels, green lines etc and the system froze up), each time I restarted and it was all OK again. Yesterday it crashed but when restarted it wasn't OK; the display messed up a few minutes into operation each time. Many times it's messed up from the moment it's switched on. On the occasions it starts up OK and then crashes, the whole system freezes. On the occasions it's messed up from power on, I can still use my machine but it's difficult to use because of the display. Uninstalling/updating/rolling back drivers on the graphics card had no effect, and the fan on the card is working fine (although it never goes above 30% - I don't know if this is normal or not). The temperature on the card is also fine. There appear to be no lose connections inside the machine. I've run a memtest, which shows no problems there. I've checked my voltages, which show 3.33v on the 3v, 11.4v on the 12v and I can't seem to get any results on the 5v. I get periods of time of varying length when I can use my computer just fine with no issue, and then the problem usually occurs like this: 1 - In the middle of operation (usually when I'm doing something graphically intense, but not always) the graphics go weird and the system freezes. 2- I switch the power off and on again. It starts up with the graphical problem still present, but the computer is usable. I start in Safe Mode. It often displys a "Windows has recovered from an error" message when I sign back in. 3- I disable and uninstall the Graphics Card, and restart the computer. 4- Using the onboard graphics at this point, the graphical problem still often persists. I run Windows in normal mode and reinstall the graphics card. 5- I restart the computer and run it in normal mode, using my Graphics Card. It generally starts up fine, but then crashes (and freezes) about a minute after sign in. 6- I repeat steps 1-5. Usually, if the graphical problem is no longer persisting at stage 4, then it will no longer crash at stage 5 and I have a few hours of computer use because the problem occurs again. Anyone have any suggestions/advice? Some people have advised me that it's likely to be the graphics card, others are sure it's the PSU. Being not particularly rich, I don't want to fork out to replace the wrong part! The fact that it often persists after uninstalling the Graphics Card (reverting to onboard) would suggest that the card isn't the problem, although I can't be 100% sure as I can't physically remove the card because there's nowhere to plug my monitor in on the motherboard. I've been using this system for nearly 2 years now, my card is a MSI GeForce 8800GT 512MB, my motherboard is an ASUS S775 Intel P35. I was running 64-bit Vista, I did a clean 64-bit Windows 7 install today and the problem still occurs with no more or less frequency. My PSU is a rubbishy 480W one that came with the case. Many many thanks to anyone kind enough to help.