Please help, tons of flashing pixels cover my screen

[hellataz]

Hello, I really need help! My iMac has been having issues for months where these random colored pixel pop up all over my screen. Often I can wipe them away with a window I have open on my desktop. My boyfriend thought my iMac just needed to be reformatted. So I backed everything up and erased everything and installed the newest os. And the problem is now worse. Twice as many flashing pixels, some won’t even go away. And colored lines around my dock now too. It’s a mess. We were able to make them go away by booting in safe mode, but there was nothing installed other than the high Sierra OS. and I also did two hardware test (regular and extended) both came out ok. I’m at a loss. Is this something that can be fixed or do I need a new iMac? It’s a 21.5 inch iMac (mid 2011) 2.8 i7 intel processor, 16 gb memory, and an AMD radeon hd 6770m 512 md graphic card. Oh and I’ve also been experiencing several kernel panic and my iMac has been restarting itself frequently. Please help.

 

[Raz0rEdge]

Those types of graphical artifacts are usually indicative of a GPU issue. If they can be "wiped" away by moving a window around, it's just beginning to fail and will get worse as time goes on and the issues will either persist regardless of what you do.

Grab a copy of Cinebench, a graphics benchmarking tool, and see what happens. This application will stress the GPU primarily so if you start seeing issues, then you should start thinking about possible fixes (replacing logicboard or upgrading to a newer iMac)

 

[hellataz]

thank you I will try that.

 

[Raz0rEdge]

Thank you for the images, that's very informative and does further indicate that it's a failing GPU. The problem will worsen over time, unfortunately as the GPU continues to fail.

 

[hellataz]

Not sure what this means but I ran the test and got these results. also a bit of pixeling appeared during the first test.

 

[MacInWin]

That's a pretty old iMac, and may or may not be worth repairing. You can check at ifixit.com to see if it can be fixed, and if you want to try it, assuming it can be.

Unfortunately, this site is being closed by the owners on December 31, so we won't be able to assist you hear. If you want to keep in touch read this thread about the closure and what the admins/moderators have decided to do:

http://www.mac-forums.com/news-and-...44599-mac-forums-shutting-12.html#post1781568

It is long, but most of the posts are short. Look for dtravis7, slydude, chacag posts for the efforts.

 

[Raz0rEdge]

The values from Cinebench aren't important, interesting for other purposes but not here, it's really a way of putting more stress on the GPU than your normal usage to see if that would exasperate the issue and make it appear worse or more often. Again, there isn't a software fix for the issue, it's either an expensive logicboard replacement or upgrade to a newer iMac.

 

[jasongoldworthy]

hi there,

its a failed GPU

if you go to the famous selling site you will see many replacement GPU's for this iMac
it is time consuming but can be done,