2012 iMac Graphic Glitches

[s.m.t.]

Getting square graphical glitches seemingly at random... Cant tell if they are due to a hardware issue or if is it software related... I see them at various places in the OS. Changing what is on screen sometimes makes them go away... Meaning if they show up on the log in screen, they go away when loging in with a user. Or if they are in a application, you can minimize it and they go away, ect... They are also never in the same physical location on the screen or the same pattern...

Anyone seen these before?

 

[andy9l]

Looks like a dying GPU I'm afraid.

 

[s.m.t.]

guessing on a late 2012 iMac that means changing out the logic board?

It appears this morning they remain consistent at the log in screen... Have two users setup, log in as each they disappear... Return the log in window they reappear... Never been that constant before. But reboot and they don't show up on the grey screen until the log in screen returns... Seems as if it was a hardware issue it would be persistent no matter what is on screen yes?

Going to try booting an external drive and see if it shows up...

 

[matreya]

guessing on a late 2012 iMac that means changing out the logic board?

It appears this morning they remain consistent at the log in screen... Have two users setup, log in as each they disappear... Return the log in window they reappear... Never been that constant before. But reboot and they don't show up on the grey screen until the log in screen returns... Seems as if it was a hardware issue it would be persistent no matter what is on screen yes?

Going to try booting an external drive and see if it shows up...

Given this behaviour I would be suggesting it's a software problem, and suggest you reinstall the OS...

What version of OS X are you running?

 

[s.m.t.]

I just tried booting an external usb disk and no issues at that login screen or anywhere else, but upon rebooting back to the internal disk, they are back...

This is the first time I found these glitches to be so predictable...

Running Yosemite 10.10.2

 

[strukt]

Reinstall your OS fresh. No issues now? Yay

If the same thing happens, you GPU is giving up and needs replacement.

 

[kepler20b]

no that looks like classic gpu failure (failing) to me. it's artifacting.

slowly but surely it will get worse until total failure

 

[MacVidCards]

Try running an OpenGL benchmark like Valley.

Will be pretty obvious

 

[s.m.t.]

Try running an OpenGL benchmark like Valley.

Will be pretty obvious

Thanks for the suggestions, will give it a try...