Horizontal lines appear on iMac bezel

Question

Level 1

30 points

Horizontal lines appear on iMac bezel

I have an older iMac which works fine, and is currently only used to watch streaming movies etc. I just noticed today, that there are weird horizontal lines on the bezel, on one side only. Photos attached.

No liquid has ever been used on the screen, and nothing has ever been spilt on the iMac.

Any idea what might have caused these lines? I don't see them on the actual screen itself, just on the left and bottom bezel. Apologies for the huge photo. There was no option to reduce the size.

Posted on Apr 16, 2026 6:47 PM

Reply

Answer 1

den.thed

Level 10

96,762 points

Apr 16, 2026 7:27 PM in response to Justakiwi

That looks like thin light beams shining thru the blinds on a nearby window.

Reply

Answer 2

den.thed

Level 10

96,762 points

Apr 16, 2026 8:48 PM in response to Justakiwi

Beside the lines, I see a slightly darker spot that looks like it could be heat damage.

If it is getting hot..? Make an appointment at your local Apple Store or AASP.

Find Locations

Reply

Answer 3

Old Toad

Level 10

217,870 points

Apr 17, 2026 3:55 PM in response to Justakiwi

What is the year and model of iMac. You can get it via the  ➙ About This Mac menu option.

Reply

Answer 4

Justakiwi Author

Level 1

30 points

Apr 16, 2026 9:34 PM in response to den.thed

I can't imagine it is operational heat related, as I am now only using it for maybe 2 hours a day, only to watch streaming movies. I now have a Macbook Air for my primary computer. The only thing I did just think of, was maybe the sun has been shining on that section (through a window) at some point, without me noticing?

Reply

Answer 5

Apr 19, 2026 6:27 PM in response to Justakiwi

Justakiwi wrote:

Thanks for all the help. Weirdly enough, those lines have since vanished! I am thinking maybe it caused by the sun shining on it, but no idea what that would have resulted in lines like that.

No sign of any lines today, so might be one of life's unsolved mysteries 😉

Could have been caused by a reflection instead of direct light or sunlight.

Reply

Answer 6

Justakiwi Author

Level 1

30 points

Apr 19, 2026 4:29 PM in response to Justakiwi

Thanks for all the help. Weirdly enough, those lines have since vanished! I am thinking maybe it caused by the sun shining on it, but no idea what that would have resulted in lines like that.

No sign of any lines today, so might be one of life's unsolved mysteries 😉

Reply

Answer 7

Justakiwi Author

Level 1

30 points

Apr 16, 2026 8:21 PM in response to den.thed

Nah, not that. No blinds and the lines are there all the time (day and night) so not a reflection thing 😊

Reply

Answer 8

Apr 19, 2026 4:15 PM in response to Justakiwi

Did it spend a lot of time with a pattern like that shining on it? could it have faded?

Reply