fplanque: dev blog

Did you know there were actually 5 different fans inside a Mac Pro (early 2009 version)? They are named Intake, Exhaust, BoostA, PCI and Power Supply! By default, all of them turn pretty slowly; in the 600 to 850 rpm range! Which makes the whole thing pretty silent… yet… anoying because of the complexity of the sound (yes, it’s 5 different spining motor sounds combined, not to mention the hard drive spinning!)

You can monitor that with iStat menus – which is very cool for monitoring a lot of things, except voltages & power consumption which do not seem to work, at least on the Mac pro 2009.

Now my problem is I’d like all these fans to run faster! Yes, faster! Not because I want some extra fan noise, but because I believe Uncle Steve pushed it too far when he asked his engineers to reduce the fan noise! I wouldn’t mind the noise to be a little bit higher pitched than it currently is.

I first tried FanControl from Lobotomo Software. BEWARE: it’s a pain to uninstall (unsinstall instrutions on their page). Because it’s designed for the macbook pro (yes, the laptop), it only controls 2 of the 5 fans and the minimum speed it allows is 1000 rpms. Up from 600 rpm, that is too much! I wish I could run every fan at 850 rpm!

Then I found smcFanControl from eidac. That one has the advantage of allowing settings for all 5 fans on the mac pro. However, again two of them cannot be set lower than 1000 rpm. Worse: it doesn’t actually do anything on the mac pro. It probably works on other apple computers but on the mac pro 2009 it has absolutely no effect on fan speed. :’(

From what I undrestand the fans are controlled by a chip called “SMC” as in “System Management Controller” and apple doesn’t give you much control over it, apart from a clunky procedure to reset it! Note: resetting the SMC allowed me to get back to original rpms for all fans after FanControl had messed them up. Resetting teh SMC also seems to have reduced the tempearture of the air mesured at the exhaust – at equivalent fan speeds and system load (that is: idle!). Strange…

If any of you knows a way to effectively control fan speed on the mac pro, please let me know.

I’d be up for some watercooling too :)