Earlier I was playing sleeping dogs on extreme with the high-res textures pack on a 7850 with an i3-3220.
Mid cut scene (About 20 mins in, Just got released) the computer crashed and would not boot. I eventually got it to boot after clearing the CMOS (Not necessary) and removing the 6 pin pci-e connection to the graphics card.
The fans were going a bit intense, but I have a Zalman Z11 Plus case with 5 fans plus a aftermarket fan on the CPU.
GPU only has a singular fan and is 2GB.
I put the card at the top of the suspect list because it's unlikely that you would damage a rail for the GPU without some other component having an issue too. (But it is possible)
It's also possible that the slot for the card has an issue, (motherboard) but the real "stress" should come from providing power an that seems to be done through a direct connection to the PSU in this case.
When you say won't boot, can you describe it a little better? I mean, was it not turning on at all? Was it powering on but shutting back off before getting anywhere? Are you at least reaching the BIOS before it shuts off? Or is it powering up but you're getting no picture?
I was going to move the GPU to the other PCI-E slot to test it, but to do this you have to permanently snap off 2 slots of the case. Leaving a chunk missing out of the back. May do this, but I want to get rid of any other causes first.
It does post, both on DVI and HDMI. The motherboard screen flashes up (Where it tells you what key to press to go into BIOS), I have tried spamming Delete but nothing. After this flashes on and off, nothing more is shown. No input is detected but the PC carries on as normal (No fan stoppages, crashes). White gigabyte screen flashes, loses input. The ports are being used on the graphics card, so I am getting a output... if only for a second.
I have tried changing the cable to the other PCI-E power connector on the PSU. No effect. Fan spins as it did before.
I'd try to put it into a different pci see if it works as that's the easiest solution (unless you got another computer laying around). You wont have to leave a whole in the back of your case if you really don't want to there is always to rig something like that back together. Specially since it's nothing vital or gonna be taking a beating (hope not anyways lol).
Though it does sound like you video card went out. Even if it posts doesn't mean anything. Just means it's not quite dead yet.
Update: I changed the graphics card over to the other PCI-Ex16 slot on my motherboard. This resulted in the computer booting then crashing and restarting. After the reboot it carried on as before: Posting but not loading windows.
I have contacted XFX and hopefully it will be covered under the warranty supplied with the product.