Very Weird iMac Screen Problem

malph · August 4, 2011 10:09AM

Bottom 2 inches of screen rapidly flashes content of top 2 inches of screen. Flashes whether computer has just been turned or after 3 hours of use. Flashing can stop for several minutes and then start again. Nothing nearby to cause electrical interference. All other functions work fine, including using the cursor.

See YouTube of problem at http://www.youtube.com/watch?v=l88-sqgpflw

24" iMac purchased in June, 2008. 3.06 GHz Core 2 Duo

OS X 10.6.8 Passed all tests conducted with the TechTool Deluxe app that came with computer. Have reset PRAM.

Is this iMac about to die? If so, I?ll buy a new 27" iMac. And if I do have to get a new computer, can I salvage the HD of the 24" iMac and put it into an enclosure to be used for backup storage or as a bootable disk so I can run my pre-OSX Lion programs?

Marvin · August 4, 2011 3:50PM

If you boot up in safe mode holding shift, it will disable your GPU and you'll know if that's what is messing up. Also try an SMC reset:

http://support.apple.com/kb/ht3964

malph · August 4, 2011 4:17PM

Quote:

Originally Posted by Marvin

If you boot up in safe mode holding shift, it will disable your GPU and you'll know if that's what is messing up. Also try an SMC reset:

http://support.apple.com/kb/ht3964

Tried safe mode boot and SMC reset - still have the flashing screen. Grrrr. Any other ideas?

Marvin · August 4, 2011 4:54PM

Quote:

Originally Posted by Malph

Tried safe mode boot and SMC reset - still have the flashing screen. Grrrr. Any other ideas?

Have you tried plugging it into a different power socket in your house? Remove any extensions if you are using them. Also try leaving it unplugged from the power for a while e.g overnight.

Also run through the hardware diagnostic on your install disc (boot up holding the d key).

You can try removing your RAM sticks one at a time too.

Very Weird iMac Screen Problem

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