Video card upgrade = nasty as hell fumes!

I recently replaced the stock Radeon 9600 video card in my mid-2005 G5 PowerMac with a used 9800 Pro, and the machine has been pumping out a nasty, eye-burning stench ever since. At first I thought it was car exhaust leaking in from outdoors, since that's exactly what it smells like, but after almost two weeks of this there's no denying that it's coming from the computer.

While there's no problem with the video itself, the fan on the "new" card has sounded labored and worn out since I first fired it up. I'm just going to go ahead and replace the cooling assembly, but is it too late? Can anyone tell me what might be happening, whether I have already cooked the card or worse? And what exactly do you suppose this vile stuff I've been breathing actually is?

I've had some odd hardware problems in the past but this takes the cake.

 

It's not really a burning smell. It smells like petroleum and metal.

At any rate, I'll be removing the card and its power cable and examining both today before I replace the cooling fan. Anything I should be looking for?

 

I did, at the very least, get the old fan assembly off. The thermal paste is little more than a dry, cracked and filthy residue at this point, and I doubt there was any kind of seal between the heat sink and the processor. Could this have been the problem?

The card is used, and while the seller has said he will take it back my only alternatives are another used card or no card at all.

Incidentally, the smell lingers now that the original card is back in place, though it is nowhere near as intense.