I've had a Poweredge 830 tower server sitting idle in my spare room for a couple of years. I used it for a while as my main downloading machine but when I picked up an SC440 and compared fan noise the 830 went in the cupboard.
The other day when fiddling with reducing the fan noise on a Precision 370 using an OEM PWM fan with this adaptor cable http://www.frozencpu.com/products/8469/cab-152/FrozenCPUcom_4-Pin_PWM_to_5-Pin_Dell_Adapter_Cable_-_8_Length_CB-PWM-D5.html?id=nqMXvpT4 I wondered if I could do something similar with the 830 (my SC440 was sold for purchase price one year after I bought it - bargain!).
Cut a long story short I picked up a low-noise 120mm PWM fan, attached the adaptor cable above to the standard PWM 4-pin plug and then removed the cables fan's 5-pin plug and inserted the wires into the existing DELL fan's 4-PIN PWM plug. Works just fine. I don't know if the adaptor cable is strictly necessary - but the metalic ends on the new OEM fan were not the same design as those on the factory-shipped DELL fan and I didn't want to do any bending or clipping.
Anyhow - noise levels are fantastic - even at boot up. This machine could sit in a quiet office and not bother anyone. I've got a nice download work-horse again just in time for all the BBC Christmas specials. I should add that I'm only using this for light-use and storing non-critical data. I guess there was a good reason DELL installed such a monster fan in the 830 - or at least I hope there was.
Wonder if an 830 likes Windows 7? I'll report back.