Boots, Fan runs fast, then black screen <<SOLVED>>
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My computer starts up, all 4 LED lights are on solid green. After about 5 minutes the fan speed starts noticeably increasing. 5-10 minutes later the screen goes black and the #4 LED goes off, leaving LED's 1 through 3 solid green. The iMac doesn't shut down and fan continues to run until I hold power button down to shut it down.
If I restart immediately, the screen lights up & the same situation happens. If I wait for a while to reboot, it seems to cool down & the fan speed is normal for about 5 minutes and the same symptoms repeat.
I have: held power switch down with power disconnected for 10 seconds, reset PRAM, installed a new HDD & tried fresh install of Mountain Lion (only because had to get data off previous one).
Any help greatly appreciated!
iMac 24" 2.8 GHz EMC No. 2134
<<Answer to question, Nothing happened before this starting iMac was working fine & no electrical surge issues >>
**Problem Solved, I decided to take my iMac in to local repair shop, the replaced the video card for $250. Unfortunately they didn't Zap the PRAM so I kept getting error messages when trying to install Lion or Mountain Lion, but after zapping PRAM work great. Thanks very much for the replies !!!
Archived as not answerable by oldturkey03