I have two 9800GT video cards that I run in SLI. The fans, for whatever reason never seem to go over 50%, even though they idle at ~70C (holy crap). I decided that this wasn't good and that I wanted something quiet (or silent) that kept my temps down.
I got two of these coolers and this thermal compound.
Because the coolers are so big you need a 12cm ribbon SLI cable. Mine is in the mail somewhere, so I decided to install one of the coolers so I could compare the temps.
After install I load up EVGA precision, a real time overclocking tool that monitors the cards. What's the difference? How about 14 degrees Celsius? The card with stock cooling and a fan at 50% is at 74C and the fanless cooler is at 60C. Nice!
I'll post pics once everything is finished. I just did a complete rebuild with some half decent cable management.