原帖由： Baschtl ,
I had an interesting endeavor with a Mid 2011 iMac 27”. I wanted to replace the broken harddrive with a new 2,5” one and add an SSD on top of it. I got the cable for the second drive and was able get everything up and running - except that the fans were running at full speed shortly after switching the iMac on. The first thing I came across was the issue with the non-standard HDD temperature reporting. I stumbled upon https://www.elvikom.pl/imac-21-5-27-blad-4sns-1-40000000-th00-9-000-po-wymianie-hdd-t50744.html which describes that you can shorten two pins on the harddrive to let the iMac think temperature is normal. I did this on a Sabrent converter frame (3,5” to 2,5”) to avoid soldering directly on the harddrive. Guess what? Fans still spinning at full speed. Then I tried the OWC OWCDIDIMacHDD11 which is similar to the solution offered by iFixit to add an external temperature sensor for the HDD. Aaaand it was still not working. Fans at full speed. I was a bit out of ideas. Some weeks later I gave it another try. The whole time I was running the iMac with the display removed to make things easier while in repair. I had it connected to an external display. I ran the Apple Hardware Test and it showed me this error: '''4SNS/1/C0000008: TL0P—124'''. I found out that this is a problem with the display temperature sensors. And indeed they were not shown by Macs Fan Control. Obviously, this was due to the fact that I didn’t have the display attached, However, even after attaching it I got the same error and fans spinning at full speed. I removed the display again and found the temperature sensor on its backside. I removed its connectors and re-attached them. Then I attached the display again and tried starting the iMac without the additional OWC cable (i.e., only with the soldering solution). And it worked! Fans were quiet and I could see the display temperature sensors being shown by Macs Fan Control. In the end, it seemed to be a problem with connectors of the display temperature sensor. So the iMac didn’t recognize them and turned on the fans. What a ride.