I have been running a non-PWM fan on my CPU heatsink ever since changing it from the standard fitting. PWM fans are easy to recognise as they have a four pin connector instead of the usual case fan three pin type.
The fitted fan on the new heatsink was a seven blade 2000rpm three pin type which was ok but maybe not doing the best job. The new fan is a CoolerMaster Excalibur nine blade 2000rpm PWM type, and it is super quiet. The old SilenX fan has been repositioned to take up the spare fan mounting in the top of the case.
So, now I have one 140mm and three 120mm case fans plus the new CPU fan.
The result? All hot parts of the motherboard now run a couple of degrees lower than they did, the CPU runs three to four degrees less than it did at idle, and I still can’t hear the fans.
Now for the not so good part.
The SilenX HA4 heatsink had a bad design flaw. It wasn’t large enough to take a 120mm fan and the fixings for the fan are too widely spaced for anything smaller. I had to use thin gauge craft wire to attach the fan to the heatsink, and I am just lucky that it all works as well as it does. However, I will be changing it out in the not so distant future for a CoolerMaster V8.