I've got a heatsink (made by a company called Speeze) which uses a 70mm fan at 4200 rpm. It's a bit noisy, but I've been having trouble finding a suitable replacement. Nexfan has a few, including a pair of the Y.S Tech TMD fans, but all of them look about average with regards to noise. Any recommendations where I can find something silent?

If not, I'll probably look at one of the fan speed controllers instead.

-Guppy[/url]

If u want something silent on on the cheap try running the fans at 7V with the 7V trick, just get a molex connector and wire the 5V wire to ground on the fan and the 12V wire to the 12V rail, the best way I found to do this was with a 4 pin molex splitter,
I have a 70MM fan HSF setup as well but what I managed to do was using zip ties to make a holder and stick on a nice and quiet 80MM panaflow L1A to it that works a treat and cheaper than buying a good quality 80MM heatsink as well, be careful with that hack above btw http://www.7volts.com was where I found the hack

Thanks for the info. It turns out that my particular heatsink will accept an 80mm fan directly, using the usual sheet metal screws to mount. I think I'll start by trying a Vantec Stealth.