Recently I was having issues with my monitor losing signal 3-5 minutes into a game, doing some research into it i notice it only happened when my card was running gaming speeds, and not if I played a game at idle speeds and that the card rapidly heated up, up to 90c in a few minutes. but I also noticed the crashing point was between 85-90c, very hot, but it shouldn't be enough to crash the computer with no warning. So I dragged a high speed fan in, and pointed it directly at the card and was able to play for 30 minutes, despite temps reaching 100c. So I figured sure, must be a heat issue. So I order a cooler, install it, plug it in, and start the computer and notice a red light on the card, and no signal to monitor, so of course I figure I messed it up. But then I install a old nvidia 8600gts, and couldn't get signal on that either.
My proc is a i5-3.20ghz, 8gb ram, and a 400w power supply with the overheating card being a HD5770 400w is not supposed to be enough for the HD5770 I know, but I ran it for a year with NO issues at all, and 400w should be plenty for the 8600gts so that can't be the issue.
So I appear to be dealing with either two dead cards, or a motherboard PCI-E issue, I am broke I can't buy one and hope its the right thing so which is it most likely going to be?
Currently I am running the onboard integrated graphics and they work fine.
I know it is not dead because I am running the PC right now with integrated graphics, however yes, A dying PSU could be possible. it would explain the crashing only at gaming speeds where the card was drawing more power.
The reason I said that was the red light, the only time I had an LED come on on one of my cards is because it wasn't getting power from the cable attached. Look in your manual it should say what the lights mean, maybe it's something different, but 400w psu (without mentioning the brand) and the light on the card made me think PSU.