Chosen Solution
My 27” iMac has suddenly started the fans full speed, full time, Apple Hardware test revealed the following code: 4SNS/1/C0000008 TGOH—124 So its a thermal sensor, but which one and is it changeable?? Many Thanks
You’ll need to take the MXM GPU board off clean the old thermal paste and pads refresh the paste and replacing the VRAM thermal pads I would also recommend installing TG Pro so you can get a better handle on what your sensors and fans are doing.
