Persistent horizontal lines appear on iMac screen

Actually calling Apple Support is also the best way so they can document the call and more importantly document the issue.

I've read of others mentioning the heat in the top right corner.

As a test In Display refs try turnung on Nightshade.

These lines just appeared in my iMac M1, over the bottom dock.

Since I started to charge an apple watch S9 using one of its ports in the past month, I wonder if that is the culprit

Hi,

This problem is not rectifiable unless u change the Display hardware from apple, which is super expensive and still doesn't guarantee that it'll last perfectly after change... so no point !!

So next step is to get an EXTERNAL MONITOR.

Since most of us are so used to the iMac 5k screen monitor... it becomes difficult to adjust overnight to some other monitor... so here's the thing....

iMac M1 2021 model comes with the PPI (PIXEL PER INCHES)- 218 PPI

I stay in Bangalore, India and recently got a Dell QHD monitor for 23k with resolution QHD (2560 x 1440) with 109 PPI and it's so hard to get used to this screen... since suddenly ur PPI has dropped to half from Mac's 5k 218 PPI to Dell's 2k 109 PPI. You might see the Videos and pics quite clear... but when it comes to TEXT CLARITY... u will not find it easy for your eyes... as the clarity differs a lot (attached screenshot from my Dell QHD monitor below... as u can see the text is pixelated and not-so-clear).

Now imagine the text clarity when u try and buy a 1920x1080 resolution monitor... which will have below 100 PPI display quality.... hence the text readability will be still worse.

So my suggestion is to go for a 4K monitor which comes with a higher 163 PPI display for a better TEXT clarity on screen.

My current DELL QHD monitor costs me 23k and the next version 4k monitor costs 30k upwards. I'm now forced to return this QHD monitor and go for the EXPENSIVE 4K monitors... bcos Mac won't do justice to the display screen with lower PPI :(

Dear Blackfriars21,

According to Apple support, it's an LCD malfunction and the only solution is to replace it.

So it's not a software problem.

It's a hardware problem.

That's already established.

Same situation as well, bought mine in September 2021 and the lines started to appear in March 2023. At first I thought it was just me but seeing all the responses here, this is clearly not an isolated issue.

Was putting off sending it for repair since I was hoping the display will go back to normal by itself over time, since the lines tend to flicker and on some days they take up less of the screen.

However in April 2024, it got so much worse with the lines completely taking up the display, rendering it impossible for me to navigate or even use the computer itself.

Would like to ask if there’s a recommended adaptor or cable to connect my M1 iMac to an external HDMI display so I could access and back up my files? Much appreciated!

I have an iMac, bought in 2021. It has been perfect until today. Totally out of blue, flashing horizontal lines appeared in the screen. After a while, the lines "stabilized" and reduced to a single line (see in the attached photo). Apple, please help bring my iMac to normal. Thanks!

Thank you for taking the time for this wonderful technical details of the issue! :) I trust it will be resolved for the highest good of all.

@jotap62 see my last response to @jot because I cant repost it or they delete it.

Any questions let me know!

Hi, could those of you who have this problem check where your model was manufactured? You can check under the base/foot/stand, there should be a label that says 'made in' or 'assembled in'.

@VanCitySean, realy glad for you.

Thanks for your help.

I had the same issues, went to Apple service and I had to finally change the screen. The cost was 700euros, no explanation was given.. It's very disappointing.. Located in Athens, Greece.

Went to the Genius Bar, and was suggested to change the display and the cost is 700 euros. Location: Spain. Have to say this situation doesn't look nice. Hope Apple will jump in

I am a teacher on a school of graphic design and saw a student with the same problems on an MacBook Pro today (M2)... I told him to go directly back to the store because of the warranty.

I'm having the same problem. I called apple service in South Korea 3 times and went to apple genius bar, but they couldn't solve it and only recommended paid repair. They asked for 850,000 won, which is the same price as a used M1 iMac. I used the iMac in a fixed position and didn't do anything to cause it to break down, it's so unfair. I don't know if I'll be able to buy a Mac in the future.