CPU fan full speed showing 0rpm
a couple of days ago I tried to change my Seagate hard drive for another Seagate but with 3Tb and also install a SSD drive in place of the optical drive.
I thought everything went quite well during the installation but when I finished it turned out that the CPU fan was going crazy. I checked several posts and seen that other people complained about fans going crazy and it was due to some sensor not working, so I tried several things but none of them with result:
- Connect the optical drive sensor to the LCD sensor socket to see if that was the problem.
- Connect the optical drive sensor to the HDD sensor socket.
- Same as before but also connecting HDD sensor to LCD sensor socket.
None of them seemed to work so I ran AHT and I got this results:
- 4MOT/4/40000003 HDD-1416
- 4MOT/4/40000003 HDD-1422
- 4MOT/4/40000003 HDD-1426
So I thought that it was worth checking if all fans and connectors were working. I first unplugged the ODD fan and connect it to the HDD fan and it worked fine, did the same connecting it to the CPU fan and seemed to go like crazy, but worked.
Finally I decided to unmount the HDD fan and plugged it to the ODD connector and surprisingly it worked.
Then I tried to limit the fan max speed via programs like SMCFanControl or SSDFanControl but with no luck, all of them reported that the CPU fan speed was 0rpm and it's the one going crazy.
So.. my problem I'm totally lost. I don't know if it's worth buying a new HDD fan and see if it might solve my problem or if I might take the same route as others and hack the CPU fan, or maybe change the logic board...
Cette question est-elle utile ?
I am currently having this exact issue. The bottom left fan is the one that's running full speed, after I swapped out a bad logic board. Could it be that the new logic board is bad? SSD Fan Control shows the CPU fan speed at 0.
par Steven Oleksiak
Some years later, I also replaced a hard drive in a mid-2007 iMac with an SSD and got the same symptoms: fans running at 100%, sensors reporting 0 rpm. However, in my case, the culprit was the CPU Fan connector being loose. Reconnected it, problem vanished. Replaced the CPU a few days later, still no problem.
That can cause the problem, too.
Please use the OWC part when replacing the original HDD with either your own HDD or SSD: OWC In-line Digital Thermal Sensor for iMac Late 2009 - Mid 2010 HDD or SSD Drive Upgrade. Many newer HDD''s don't offer the header for the Apple thermal sensor and unless you are putting in the exact same drive the sensor cable will likely not mate up with the correct contacts as each drive maker does things a bit differently.
In the case of SSD's they don't offer the needed connections at all so you must use the OWC part (when mounting it in place of the HDD)
We strongly recommend not using fan control software as it can mask other problems and over rev your fans wearing them out prematurely!