Today I installed a Zalman ZM80C-HP heatsink on my Geforce4 and switched out my Enermax "Whisper" PSU for a new Seasonic Tornado.
Thankfully my video card's stock heatsink/fan was simply held on with plastic screws; I didn't have to worry about prying anything off.
The Seasonic is certainly more silent than the my Enermax, but the real difference was made by getting rid of the stock heatsink/fan on the video card! It went from loud and whiney to totally silent!
As you can see in both pictures I had to pass one of the screws on the GPU heatsink bracket through the fan bracket for my CPU fan. This was perfectly simple enough and didn't cause any problems.
The CPU fan braket does mean that I couldn't use the optional GPU fan even if I wanted to. No big deal for me as the Heatsink itself is enough to cool my old fashioned card.
So now I have a Sunon intake up front blowing over a hard drive, one in the rear, the cpu fan, and the big 120mm in the PSU. Both the Sunon's are running at 7 volts and even if I unplug them both I can't hear a difference. I even have the 92mm over the CPU turned all the way down with its fan controller.
This makes for one quiet rig. The most noticable noise is coming from my two Western Digital hard drives. I have an 80gb and a 120gb (mounted in the 3rd 5-1/2 slot). They do make a semi-high pitched sound that I can notice now that the GPU fan is gone.
I don't know how I am going to decouple them, I will have to make a trip to the hardware store before I do anything. But from reading I get the feeling that decoupling does more to reduce low pitched sounds and won't help with the high pitched noises?
One problem I had with my case was that it had a flat piece of sheet metal for the PSU to sit on. Not a good idea if your PSU fan is on the bottom! I had to get out some tin snips and do away with it. It doesnt make for a pretty edge but it is all gone now. The case is an Antec SX600. My only other complaint is that there are no drilled holes for mounting fans, you have to use their plastic fan holders and snap them in. Not a big deal if you own a drill, but I don't.
Alright I think that's it. I have to say the documentation for the Zalman GPU heatsink is top notch! Very well done, it's even translated to english perfectly! Seasonic is also very well done, but obviously it is a lot more simple.