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Here is a weird one… I have a faulty display on my iMac so I was thinking about hooking it up to a secondary display and make use of it. When I changed the hardrive to an ssd, I tried only using a secondary display just for testing and the computer was slow as a snail! I tried restarting it and i installed the macfans app to get the fan to work properly but nothing seemed to help. The only way to make it run as usual was to connect the screen. I did not have to connect the cable which provides light, only the data cable and the computer again worked on the new display… any ideas for why this is and or how to use it without having to have the lcd connected?
This is normal!! Disconnecting the display will do this. SMC is missing the thermal sensors from the display (2) as such the system goes into CPU Safe Mode. Basically, the CPU’s clocking is reduced to prevent the system from over heating. You’ll need to put the broken display back on until you get the replacement.
