Hi, So I recently started reusing my old iMac after a couple years of not using it, I’ve been using it only in target display mode for my 2017 MacBook Pro via a thunderbolt cable and adapter and when I started the iMac up today the fans were on full and Activity monitor showed kernel_task reaching very high CPU levels, highest I’ve seen the kernel_task was at 495% today. As a result of course everything is extremely slow at the moment and it won’t enter target display mode either. I installed iStats menu to look at the temperature sensors, pictured below, I can’t seem to find anything abnormal and the CPU doesn’t seem hot from what I can tell, the fans are still going crazy though. I’ve already rest SMC, booted in safe mode, resetted PRAM but all to no avail. Apple Hardware testing won’t work - I just get an error message saying “Error: 0x800000etc, Cannot Load "EFI/Drivers/TestSupport.efi". So I’m kind of stumped as to what to do next, I’d rather not have to take it in to an Apple Store, especially at the moment.
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