Joe "Roadee" Dawson, one of Driverheavens Moderators has put up a great guide to help all of your interested in upgrading your video card cooling.
"I see a lot of members here on DriverHeaven wanting to get the most that they can out of their video cards. Games seem to keep getting better and more complex, and requiring more and more video power. Yet our income doesnt always allow us to upgrade every time the newest card comes on the market.
One of the easiest ways of increasing performance for low cost is upgrading the cooling on your video card. It is fairly easy to do, but a lot of people are understandably weary of trying it. So I figure that since I am upgrading the cooling on my card, I will share this experience with you, and hopefully help a few of you take the plunge in modding your video card. You must keep in mind though, that performing ANY mods on your video card VOIDS the warranty. So again, only attempt this mod at your own risk!!"
Read the guide here