My PC is showing symptoms which indicate a possible graphics hardware failure, but I am not 100% certain. First of all forgive me, I haven't performed common sense trial and error by trying to use my onboard graphics. My PC was factory assembled, and for some reason the VGA socket for the onboard graphics has a cover on it saying 'do not remove'. I will remove it soon, but I thought I'd ask here first.
My PC has been crashing during graphics-intensive events. It first happened during a game, and then during a high definition video, and again during watching a DVD. I have attempted to recreate these circumstances to recreate the crash. A game or HD video always does it, unless it's very simple such as a youtube video.
More specifically, the crash is usually accompanied by a Blue Screen of Death, with the message that the driver nvlddmkm.sys has stopped working, or equivalently that a graphics driver has stopped working. In the most serious crashes, the crash is preceded by strange graphical glitches such as wobbly lines across the screen, the screen goes blank (the monitor goes onto standby) and the PC does not respond at all unless I shut it down with the power button.
Updating to the most recent driver does not solve the problem. At the moment I have rolled back to a generic Microsoft driver, with no change. It does not appear to be a software problem. The strange graphical glitches/lines even appear sometimes on the opening BIOS screen.
Another interesting symptom is that the Windows Experience Index numbers have changed. My Gaming graphics rating was over 5, now it has changed to 4.7.
My PC and graphics card are about 3.5 years old and I use the PC every day. The graphics card is an Nvidia GeForce 8500 GT (not exactly amazing even at the time). I recently replaced my hard drive and installed Windows 7 on it, because the previous hard drive failed.
Replacing the graphics card would be very cheap, but I need to be more sure about what the problem is.