Chosen Solution
Have been experiencing random black screen upon waking the computer up from a longer period of sleep 10-12 hours. Screen initially lights and then goes black. Thought it may be the GPU (AMD Radeon 6970M 2gb) so ran the AHT to see if it came back with anything on it but instead got 4MOT/40000003: HDD-1333. From what I’ve found online this seems to be the hard drive fan behind the motherboard. This imac was special ordered with two drives, SSD with the OS on it and then a secondary HDD. Do you think replacing the fan will fix the black screen issue? Is there a fan for each hard drive in the computer or are they stacked in the same location? Thoughts on what this may be and possible fixes?
This model had major GPU issues and had a Apple repair program for replace it (of course, now expired). Hook it up to an external monitor to help isolate the issue. If the external exhibits to same issue, you will need to replace or repair (reflow) the GPU.
check out my short video on the problems I had. it might help. How to repair video on Mid 2011 27 inch iMac
