SSD as 2nd HD, now CPU fan doesn't work?

Warranty issues aside, I recently installed an OWC 115GB Mercury EXTREME Pro SSD as a second hard drive in my 27/i5 Mid 2010 2.8GHz iMac. I did not change any other configuration setting and the original hard drive is configured as shipped. After shutting everything up the internal fan(s) spin extremely loud (especially on the left/cpu side as you are facing the screen). I installed istat pro and while the temperatures look good to me, it says the CPU fan is not running. I've been searching online for days and can't find anyone else that has the same problem (everyone seems to only have issues with the HD temp sensor.) I've taken the iMac apart twice since the problem started and can't find anything broken, connected upside down, or plugged into the wrong spot. Has anyone by chance run into this before? Thanks for the help! I've attached a snapshot of the istat readings below.

Are you sure the CPU fan is actually not running? (I know what iStat says...) Your CPU temp looks normal - assuming the temps are in F not C. If the CPU fan is not working, the CPU will heat up very fast and the machine will shut down. Also, it could be coincidental that the CPU fan has failed and not related to the new SSD.

You might want to take a look at this from ifixit. They also have guides which may help.

chscag said:

Are you sure the CPU fan is actually not running? (I know what iStat says...) Your CPU temp looks normal - assuming the temps are in F not C. If the CPU fan is not working, the CPU will heat up very fast and the machine will shut down. Also, it could be coincidental that the CPU fan has failed and not related to the new SSD.

You might want to take a look at this from ifixit. They also have guides which may help.

Click to expand...

Thanks for the reply, I appreciate the insight! I agree that the CPU fan is likely spinning as the temps (F) are fine. The issue with the fan is that the SMC doesn't think it's there? I took a look at the link you suggested but that mostly talks about the HD thermal sensor. Unless I'm missing something, the HD thermal sensor is still working fine in my system. I didn't disconnect it when installing the second hard drive and have verified that the cable is still correctly connected to the original HD and logic board. Is there a second connector on the logic board that I can't see where I'm supposed to be hooking up a second HD thermal sensor for the new SSD, or even a splitter of some sort for the original cable? If thats the case I can try buying one of the optical drive thermal sensors.

Also, based on another suggestion I ran the apple diagnostic tool and came up with the following error code: 4MOT/4/40000002:CPU-0

No, only the main hard drive has an output for a thermal sensor. As far as I'm aware, the logic board has only one input for a hard drive heat sensor.

The AHT error you posted is pointing to a defective CPU fan. I can't be certain of the exact diagnostic error (Apple techs have the codes) but it sure looks like the fan is not working. What is strange is that the machine is not overheating and shutting down.

What you might consider: Open the machine again, remove the SSD, button it up, and make an appointment with Apple to have it checked out. I can't say for sure what their response will be with regard to the warranty, but I would think that they will honor it.

Kind of makes you think that the CPU fan is working but not reporting correctly which is why iStat can't see it and you're getting the error code. I'd still follow chsag's advice to get it checked out - as I'd be also concerned that it wasn't being controlled properly - as in, was just running at the set minimum rpm.

I appreciate the help. When I get some free time next week I'll be returning the iMac to it's original setup and then bringing it to our local Apple Certified repair center. If that doesn't help (warranty) then I'll replace the CPU fan myself.