Hi all, My late 2009 era 27'' iMac has been acting up as of late. It started yesterday and continued today. Running OS X El Capitan, whatever the highest spec on my model was, & RAM upgrade. The display will basically shut off but the computer is still on, as I can hear the processor running. I thought it might be a temperature issue and tried to download iStat Pro but it wouldn't work and now I'm back at black screen so I can't try further. No issues before this. I will continue to google around but wanted to see if anyone had any thoughts. EDIT: To clarify... boots fine, just goes black after awhile at random.