Wanting a quiet computer, I replaced rather noisy default heatsink & fan on my Asus GeForce 6800XT (http://www.asus.com.tw/products4.aspx?l1=2&l2=7&l3=3&model=769&modelmenu=1) with Thermaltake Schooner (http://www.thermaltake.com/2005/coolers/chipset/cl-g0009schooner/cl-g0009.htm).

The installation took about an hour because the instructions were somewhat misleading, some of the screws were too long, and my hands are shaky. I got it installed properly nonetheless.

In my opinion, the performance is great for a completely passive cooler.

The manual says overclocking isn't recommended (of course), but I've overclocked core 20% and memory 10%, and unlocked 16 pipes and 5 shader units (default for the card is 8 pipes & 4 shaders).

This is what the temperatures look like after running 3DMark06 default test with the case closed:

http://img387.imageshack.us/img387/3154/6800temp6sg.png

http://www.techspot.com/gallery/data/501/medium/schoo.JPG (http://www.techspot.com/gallery/showphoto.php/photo/1026/size/big/cat/501/page/1)

Although the temperatures may seem high to some of you, the system is stable. GPUs can handle the temperature better than CPUs anyhow, from what I can tell.

Next I need to get rid of CPU and PSU fans, they're the only ones left.

High temps are usually the main problem of fried (and ready to eat) boards. I suppose if the temps aren't much higher than with the stock cooler, you should be fine.