Symptoms: after changing heatsink on graphics card, computer won't turn on when graphics card is plugged in PCIE slot. When I press the power button, fans move a little bit and that's it.
The card is XFX Radeon 6850. With the card not plugged into motherboard, but plugged into power, computer boots. With the card in motherboard, with or without power, it doesn't.
The heatsink was Arctic Cooling Accelero S1Rev2. It was a tight fit, and I had trimmed some of the heat spreaders to get them to fit. When testing with Furmark one of the temperatures was much higher than others, so I decided to reapply thermal paste. After doing that was the last time the system successfully POSTed, it went like this: BIOS screen came up, GRUB came up, Windows started loading, and then the screen went black, all fans stopped, and the power LED started flashing. It continued flashing even after I disconnected power cord from PSU, and stopped at the moment I disconnected monitor.
I took the heatsink off the card again to check for obvious shorts, put it back together, still the same.
I understand that the card may very well be dead now--maybe thermal paste spilled somewhere, maybe static electricity hit at some point, maybe heatsink touched something it shouldn't have, or maybe just not delicate enough handling. Anyhow, given the symptoms, what would be your guess what's gone wrong?