Originally Posted by sabbathcrazy
I have done this many times before with my old 9800gtx+. I just rubbed some ac5 on with my finger. The 260 is a whole other story. My temps went up when I did this. The chip is allot bigger then a 9800gtx+. I am idling at 56c before it was around 45c. So how much should i use and how should I apply it?
You want to apply it the same way you would do it to a CPU.
You want as thin of a layer as possible, while still covering the entire surface. Definitely don't spread the TIM with a bare finger, as it's naturally oily. I don't recommend spreading at all, as you can potentially incorporate air, but use a credit card or something similar if you do spread it.
I personally use the two-line method and let the weight of the heatsink and the pressure from screwing it down to spread the TIM. Make the lines at 1/3 and 2/3 across the chip, and run them from 1/3 to 2/3 across the chip. This has always given me the best spread that I can duplicate.
You'll just have to get used to how thick to make the lines. If the TIM seeps out the sides, you're using too much. If it doesn't come close to reaching the edges, you aren't using enough. That part just comes down to trial and error.