Horizontal Lines on Screen of iMac, 24", 2021

What you're experiencing is a display problem with early M1 iMacs.

The following topics illustrate the Silicon M1 iMac Display problem:

Screen Failure on 24-inch-iMac, M1, 2021 - Apple Community

Persistent horizontal lines appear on iMac Screen - Apple Community

Horizontal Lines on Screen of iMac, 24", 2021

Horizontal black lines covering bottom 3rd of 2021 M1 iMac screen

Grey horizontal patches on my M1 iMac 2021 model

Horizontal lines at the bottom of iMac(M1,2021) screen

Horizontal Lines on 2001 M1 iMac Display

Persistent horizontal lines and other issues on iMac M1 display

As you've already been urged to do is take it into the nearest Apple Genius Bar for a free diagnostic test. You'll be told that the repair will cost about $600 US and that there is no replacement program currently for the problem. If you take it in you're telling Apple that there are more M1 iMacs with the problem and you'll be in their database if and when there is a repair program initiated.

Some users have opted to get an inexpensive 3rd party monitor and run it with the iMac. It's certainly less expensive than the repair costs.

Submit feedback to Apple at www.apple.com/feedback and then make an appointment at your local Apple Authorized Service Provider have it serviced and repaired. Apple has not announced any repair programs for what you are experiencing, if/when they do your out-of-pocket expense will be reimbursed.

Same problem. Same screen lines. Same response from Apple Store. Not a manufacturing issue. You just need a screen replacement. That’ll be £630 please.

This definitely needs to be an extended Apple services program. Asap.

The screen broke permanently due to the horizontal lines defect. The problem lies in a cable that also powers the LCD, which is located on one of the tops of the screen. this cable (of the FFC/FPC type or Flat Flexible Cable / Flexible Printed Circuit), has to sustain a very high voltage (around 50V) to power the LCD (despite the iMac's power supply being 15.9V), and it heats up a lot! it starts to burn out and degrade at the connector, to the point where it lets the signals leak between the various connectors and short-circuits some of them, which ends up causing those lines and in the end it breaks.

You'll have to keep tabs on this Apple site, Apple Service Programs - Apple Support. to see if a when a recall service/repair program is announced by Apple.

In the meantime you might consider getting an inexpensive 3rd party monitor to use with your iMac.

I purchased four M1 iMac 24" in late 2021 for my office, two with lowest specifications, the other two with highest specifications. Unfortunately both of the higher spec iMacs have exactly the same issue started from March and June this year. This is a 50% fail rate after three years of careful use.

It is disappointing as the issue was firstly reported as early as 2023, then hundreds of users expressing "me too" in Apple's forum, Apple seems do not care. I am sure there are many more customers who experienced the same issue but did not hit the "me too" button.

I talked to online support about my findings, also took the iMacs to Genius Bar despite hours of traveling. While I was 99.9% sure it is a hardware issue, I still followed their advices and wasted hours of playing with the software/hardware issue isolating game, by erasing all content and reinstall Mac OS. The specialists sound empathic, but the options provided are still 1) pay to repair or 2) not to repair. I don't blame them, as they are just following the company's guidelines.

I have sent a feedback to Feedback - iMac - Apple to request for a Service Program. Hopefully Apple takes this issue seriously soon enough so they don't turn loyal promoters into detractors.

If your 2021 iMac 24" is having the same issue, please also send a feedback to Apple, and post your case here. It seems the older thread is closed where I cannot post new comments.

iMac 1:

iMac 2:

[Edited by Moderator]

Keep checking this Apple website for a Service program for the M1 iMac screen: Apple Service Programs - Apple Support

Just ran into this issue on my M1 iMac, purchased in July 2021 in Malaysia. Took it to Apple and was quoted a very expensive repair cost. No compromise, no goodwill offer. Apple wasn’t willing to help at all. Really disappointing.

Keep checking this Apple website for a Service program for the M1 iMac screen: Apple Service Programs - Apple Support

Display vertex surface heating to scorching 55°C (22° more than device normal), another symptom for this issue. Apple technical support is not helpful in explaining why this happens after 28 months of normal use.

I have documented the overheating anomaly in M1 iMac (horizontal lines-issue) here:

M1 iMac Display vertex heating to scorchi… - Apple Community

Why would I get a display replacement without an explanation? This is not good. Considering this I am thinking of selling the other iMac I have at home, as there is no explanation provided.

If you are getting seizures, immediately turn off the computer and get it fixed. You could fall and get hurt.

There is no software fix, it needs to go in for a new screen.

For additional context, I have the following iMac:

iMac (24-inch, M1, 2021)

• Ports: Two Thunderbolt / USB 4 ports, Two USB 3 ports
• Chip: 8-core CPU (4 p-cores, 4 e-cores), 8-core GPU
• Storage: 1TB SSD storage
• Memory: 16GB unified memory

Ordered on: May 12, 2021

In terms of my exact symptoms, I don't think it's dead pixels. When I run a dead pixel test, I see two distinct issues:

• Along the bottom rows of pixels, there are three or four alternating black horizontal lines extending across the entire screen, just below the dock
• In the lower right section of the screen, from the base of the dock up to about 20% to 25% of the display, thicker light grey lines are visible, primarily on the right side. These lines add a textured appearance to the folders in the dock and are especially noticeable on an all-white background

L2E2 wrote:

I have a 2021 M1 iMac and am experiencing the exact same issue. Is Apple addressing this?

Not at this time. Keep tabs on this Apple site, Apple Service Programs - Apple Support, to see if and when a repair program is initiated.

Yip, my screen gave up about a month ago… not going to spend the ridiculous amount of money the Genius Bar asked to fix it, so today I bought a butt ugly LG monitor instead and I’m placing it in front of the iMac which is now essentially nothing but some kind of deformed MacMini.

Fantastic!!! Thanks Apple 👍

The amazing user experience of sleek, minimal, cable free design has become an experience of janky, ultra bulky and cluttered chaos.

Not impressed!

Listen to your customers and fix this issue!