**solved** Imac 8,1 Fan issue

[4ycr]

This is for my friend and having looked at the teardown, it is above me but before he went somewhere I thought I would ask here.

The fan is at high speed constantly, this apparently happened after a repair years ago but he has just asked me. The repair was for a faulty hard drive.

Is this fixable in the first place as it sounds like a sensor fault or could it just be a cable not being plugged in properly?

Thanks in advance

 

[altrenda]

You don't say which model iMac, but here's the story. iMacs run notoriously hot, and have few ventilation slots. They use the aluminum housing as a giant heat sink.

iMacs have a temp sensor on the hard drive used to control the speed of one of the fans. The older ones used a sensor that attached to the drive with adhesive, the newer ones have a special header on the drive that uses the drives internal sensor.

Standard replacement drives have a different header. Left unconnected, no temp signal is sent to the logic board. The board then defaults the fan speed to it's highest setting, making the computer sound like a jet plane and annoying the users.

Here is an article describing whats happening.. http://blog.macsales.com/19617-diag...ed-issues-after-upgrading-the-main-hard-drive

You can rewire the connection on some iMacs.

You can buy one of these http://eshop.macsales.com/item/OWC/DIDIMACHDD11/

Or you can use one of the fan control utilities on the market to override the sensor and set the fan at a constant speed just below hearing level, but high enough to keep the drive cool.

 

[PCX]

Or you can use one of the fan control utilities on the market to override the sensor and set the fan at a constant speed just below hearing level, but high enough to keep the drive cool.

This is what we do. I believe the one we use is smcFanControl.

 

[altrenda]

I like macs fan control. It works well and has a windows version since we handle a lot of Boot camp setups.

 

[JustInspired]

I like macs fan control. It works well and has a windows version since we handle a lot of Boot camp setups.

Nice. Thanks for the info.
(have previously used a Mac-only paid version from another company)

 

[4ycr]

@altrenda & @PCX thanks for this, it is the 8.1 (early 2008 model)

Thanks for the links very handy

 

[ohio_grad_06]

Don't work on macs as much anymore, but back when I was apple certified (around 2009), I used to use smc fan control. It may help with what you are doing, and it will allow you to create profiles that specify when temps get to level x for example have fans go to percentage xyz. Nice little utility.

 

[4ycr]

Thanks for your help macs fan control worked well. It showed all temps as normal but he CPU fan went full speed anyway. It is now controlled.