I've seen other posts about a thin red line on an iMac screen. Mine is a little different in that it's only on the desktop, but doesn't show up on any opened documents, web pages, etc. It does show through any icons that happen to be on that part of the desktop. I don't think it's an LED issue--I'm assuming that would affect the screen view of documents as well. Any theories? Thanks for your help.
iMac 27″ 5K, macOS 10.14
Test using Safe Mode.
see > How to use safe mode on your Mac - Apple Support
Accelerated graphics are disabled in Safe Mode.
Does the line go away in Safe Mode and then return after restarting normally?
Test using Safe Mode.
see > How to use safe mode on your Mac - Apple Support
Accelerated graphics are disabled in Safe Mode.
Does the line go away in Safe Mode and then return after restarting normally?
I don't think that's it. If you look at the first screenshot, you'll see that the line shows on top of a folder on my desktop. If it were part of my desktop image the folder would cover it. (And I've had the same desktop image for years; the red line just suddenly showed up yesterday). To be certain, I tried a different desktop image, and the red line is still there.
Take a screen shot & view that in Preview, move the Preview window around, if you see double lines it's a Video card/VRAM problem, if the lines do not move moving the pic around then it's the LCD or cable.
This was interesting... The red line disappeared when I booted up in safe mode. Then when I restarted normally, the line was still gone. If it comes back, is it something that gradually gets worse, or is the single red line the full extent of it? I could live with that.
Thanks for the suggestion.
What year model is the27" iMac?
Identify your iMac model - Apple Support
Does the line show up in a screenshot?
It’s a 2017 iMac (Retina 5K, 27-inch). As I said, it doesn’t show up on opened documents, webpages, etc. Thanks.
That looks more like a line on the image that you are using for your desktop background.
Does it show up, if you choose another image for the desktop background.
Thanks. When I move the window I do see double lines, so apparently it's a video card/VRAM problem. What is the best way for me to address that?
Sadly, unless you have Apple's AppleCare, it could be quite expensive.
If Apple doesn't cover you it'd be used parts & some labor. :(
You’re welcome.
We’ll keep our fingers crossed that it doesn’t come back.
Thin red vertical line on desktop
