Hey brother i have done this a few times on different cards and always use leftover noctua TIM since they give you a big plunger, its easy to spread, and works great. Notua's ITM is almost to thin, a thicker paste could work better for spreading. Remove the shroud and fan carefully likely held in by tabs or screws. Remove the heatsink four screws on the back. Do not remove the memory heatsink plate they can take IC's with them as the thermal tape does not release. Clean all the old TIM with 90% alcohol. Spread new TIM with a credit card evenly and thin on the chip face, clean up the edges if needed, and reinstall the heatsink. Make sure you have the right screwdriver for the heatsink screws i think its a 0 you get at a electronics shop or hardware store, I have stripped them out using 1 before.
Best threads out there about spreading TIM, and TIM comparison. Not much covered for GPU use but transferable info for sure. My rule of thumb is spread evenly, do not use the rice or pea method, and you can go slightly thicker than cpu coolers as heatsinks may have more variance in finish and how flat they are, but never use a lot it will hurt cooling performance.Best Thermal Paste Application Methods80-way Thermal Interface Material Performance TestEdited by ryan w - 11/22/12 at 5:05pm