Let me say it again.
If the card, assuming it's in a normal, properly ventilated case, and not in ambient temperatures outside of it's operating range, is overheating - it is faulty. The cooler is not working properly, or it is not making proper contact with the GPU.
Faulty. Not working. Damaged. Broken. Flawed. Malfunctioning.
I just don't understand the mentality of spending easily the cost of a new card on "fixing" the problem, vs. getting a replacement card from the manufacturer under warranty.