Yeah, I'm using speedfan on my rig now. I currently just have a CPU loop going at the moment.
My Swiftech MCP-35X throttles via it's own PWM controller, and my four yate loons throttle via the sunbeam rheosmart, both off of the one CPU header.
I use speedfan as my software control because MSI is lacking bad in this area. Asus and Gigabyte both have good software that will do even better. For me I'm simply using speedfan so that my system normally operates at 28% PWM. At 28% my pump completely silent at 1150RPM, and my fans dial down to 1000RPM. It runs like this 99% of the time except when I do something major like gaming or rendering video, etc.
I use a 42C CPU temp trigger to ramp up from 28%PWM to 70% PWM.
My ambient noise level went down from 42dbA to 35dbA which is very noticeable and I'm not giving up any performance. When I game, I have my headphones on, so I don't even notice the ramp up.
Here is a speedfan log of my ramp up and down of fans and pump.
Benefits are obviously noise, but also saving the life of the pump and fans. It makes no sense to run everything at 100% all the time if you are not loading 100% all the time...
I think speedfan could control GPU temps as well. I have also heard of people using the PWM header on the video card to do the same thing.
OEM HSF have been using PWM for a while now, just not many take advantage in watercooling. But with pumps like the 35X and fan controllers like the rheosmart, it's not costly to do anymore. Well worth while if you really enjoy the quiet..Edited by Martinm210 - 4/14/11 at 11:18am