Jul 06, 2014

How to stop cooling fan from on Mac from constantly running at max speed after HDD replacement?

I’ve replaced drives in the past on countless PCs, but when I helped a friend do it with a HDD on his iMac we ran into an issue; Now the fan constantly runs at max speed. I was not expecting that to happen. How can I get the fan to function normally?

I'd contact the HDD manufacturer and check with them. You may also want to ask the folks at the Apple store if they have an idea why it's happening. There might be something you can tweak to stop it from happening.

If this is an Intel powered Mac, then I'd suggest smcFanControl: http://download.cnet.com/smcFanControl/3000-18487_4-102230.html



I’m not sure why Apple came up with this design. The conspiracist in me would note that it is a very good way to force more Apple owners to have their HDD replaced by Apple itself, which is of course the most expensive option for consumers and the most lucrative for Apple. In any case, Apple’s proprietary firmware on the OEM drive sends temperature data about the drive so that most aftermarket drives will cause the computer’s cooling fan to default to full power. There are a couple of ways to deal with this. The easiest (other than paying Apple top dollar) is to get an aftermarket HDD with this addressed in its firmware. Western Digital Scorpion Black is one of the few choices if you go this route, although I’m sure there are a few others. Otherwise, I think that you have to short two pins to keep the fan from spinning up, but I’ve never tried that myself.
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