Chosen Solution
I recently disassembled my iMac after it stopped booting and I suspected a graphics card malfunction. I fixed up my graphics card and after reassembling my computer and booting it up noticed that the optical drive fan was continuously on. I installed iStat Pro to see what was going on and noticed the drive was running at around 3800rpm. I just finished taking the computer apart again and made sure that the cables were all plugged in. After piecing it back together and booting it up the problem still persists. My best guess is something is wrong with the sensor on the optical drive but I don’t know. Any ideas?
It is not the greatest solution but you could use Macs Fan Control to tone down the fan RPM. https://www.crystalidea.com/macs-fan-con…
