When I turn on the pc some pink and black stripes appears over the screen, before the OS starting, and in the BIOS. I formatted the pc and the problem just keep going on.
I'm almost sure that is a graphic card problem (Nvidia 8500 GT), and that changing it I will resolve the thing, but I don't have another computer to check, and I need to be 100% sure before buying another card...
Do you think I can buy a new graphic card without any risk?
More aboutgraphic card failure
I had the exact same problem a couple of weeks ago (9800 GT). Replaced the video card, and all worked just fine.
the video card is failing, you'll have to get a new one