When I was a poor student, I spent all my savings on a Radeon 5970 for Bitcoin mining. After about a week of mining I noticed the VRMs were getting very hot. I removed the cooler and thermal pads, and since I didn't have any new thermal pads and I couldn't get any in this country, I used thermal paste instead. Result: The VRMs blew due to insufficient contact between them and the heatsink.
I was VERY upset. Luckily, the price of Bitcoins increased dramatically and I walked away with over $US8,000 in my bank account so the card paid for itself (and then some) after just a week of mining!