LATE 2015 5K iMac 27inch with weird display issues

[captainmac]

Anyone have any experience with a 5k 27inch that shows strange video-issues? Dragging windows across the screen causes weird laggy display-issues; tearing image and weird reboots. Is this a videocard issue? I have tested with knowngood RAM already, but cant find any schematics/boardviews for this thing.

 

[dukefawks]

The reboots confirm this is a GPU issue. Check if under 2 years old and in EU, then Apple will fix. I would not not even touch GPU on these as I suspect it may be VRAM or board trace issue.

 

[captainmac]

Ok the reboots haven’t happened so far with the internal HDD removed (could be coincidental). Could it be something else in that case? I am trying to doublecheck if anyone’s had any other issues as I don’t have any test parts for this model

 

[dukefawks]

I gave you some advice and got 0 feedback on it.....

 

[captainmac]

No sorry, i am going to take that advice to heart, I wasn’t clear about that.
Was just asking to check if it might also be related to some other issue than the gpu...