My HD 4770 stopped working after I replaced the stock thermal paste with Artic Cooling MX-2. Here's what happened exactly: I overcloked my card with Riva tuner to 850 MHZ core and 950 MHZ memory. Seemed pretty stable, but ultimately I revered back to factory settings (750 MHZ and 800 MHZ respectively). Now everything was fine. I wanted to test my MX-2 thermal paste against the stock one, so having two HD 4770, I took the one I was using out, put the other one in, then ran Furmark, while I was applying the new thermal paste to the HD 4770 I had taken out. After this I put the card back in (with MX-2 applied) and.... it simply doesn't work. The fan starts, but the card sends no signal. I put the other card in (the one with no MX-2), and it works. Now, I used 99% alchohol to clean the old thermal paste and used MX-2, AFAIK, these two compounds are not conductive, so I don't imagine there could have been a short circuit. I also tried the card on another PCI-E slot, and it won't work either. Does anyone have an idea what might of happened? The card was working fine until I took it out and applied new thermal paste... EDIT: just learned that alcohol is conductive. I guess a short circuit is a very likely explanation.