Good.
My CPU fan is controlled, of course --- and I leave it entirely to the bios. Anyway, my cooler is a monster, and the CPU temperature is well below 40 (34C just now) with the two 140mm fans at less than 1,000 RPM.
My Coolermaster Excalibur is under Linux fancontrol control, which means I can configure how it responds to sensed temperatures. It is not too bad at around 1,500 (general case temperature, just now, 41 --- I'd like it to be lower) but would be a roarer at its uncontrolled max 2,000.
Antec Tricool have their own three-speed switches.
The Silverstones: can be pwm-ed (sounds like something nasty hackers do!) but I'm using 12/7/5 volt adapters to supply 5 or 7 volts.
My 850W power supply is a bit like a big Merc at 40kph ... it doesn't even purr: the fan is absolutely silent. According to my UPS, my PC actually
draws about 112W!
A side fan, or even grill, would be good for getting air to the CPU, especially if it has a down-blowing cooler. However, my CPU (also being used, mostly, at a small percentage of capability) is actually the coolest thing in the system!
currently:
Ambient: 28
Disks: 36, 38
System temp: 41
N. Bridge/GPU (built-in): 39
CPU: 34
I don't actually know
what "system temp" is sensing!
The system is
not silent, although I don't think I hear much more than air moving (invitation to audiophiles: listen to my PC, you can hear the "air"

). It is, however, completely masked by an AC machine, and mostly masked by a fan on "2" or more.
At 2.0am, with no crows, nearby builders, fans, ACs etc etc, I can hear it over quiet passages through the open-back headphones

. Should have gone for
one of these 