iMac 27 inch 2020 - Screen Glitch (Random Lines Appear on Screen)

Same here. At first I only had the flickering/sharp corner on selected apps. Then after 2 weeks of use I have got 4 instances of the white line within 4 hours of use. Any knowledge on how you can trigger it? What are you guys doing when it happens?

I have the 5700xt

I have the 8GB ram, would adding another 8GB in another slot help? I'm concerned with the apparent randomness in frequency in which the glitch happens in different peoples' system, I use dark mode on a dark desktop with Dark Reader plugging for safari, and notice the glitches 4-5 times a day on a bad day, and none on a good day, I have another week to decide to return it.

I have the 8 core 5700XT, 2TB, 10G ethernet, nano matte display

Ok that suggests it’s a software/driver issue based on the glitch appearing in relation to cursor and active window positioning, as apposed to the glitch appearing across the entire screen irrespective of the active window and at irregular locations - that would suggest a hardware issue. I hope Apple comes up with a software fix soon! This has been happening for a while now.

Confirmed (at page 58): https://forums.macrumors.com/threads/imac-2020-5700xt-graphical-glitch.2251034/post-28921285 .

Evidently, the 2020 iMac 27 was not compatible with the Preview versions of Big Sur until beta 6.

When I was dialog with Apple (some weeks ago) they were less interested in the random lines glitch and had much more focus on the entire system crash that I experienced on my unit when playing games. Their focus can of course have changed since then, but when they called me up that was the main concern as I understood it. Now I wonder if I should order a new unit with a non-XT GFX, but would that GFX be able to play any sorts of games? Looks weak compared to the 16GB XT.

I dont think these are in general “riddled with issues”.

It seems like all of the 5700XT models have the flickering squared corner on some apps. It seems very reproducible. And all have to some degree the white line. Mine didn’t show any white line for 2 weeks. Then 4 times in a day and now nothing for several days. Other seems to have it nearly hourly. Maybe I’m half blind or less observant, but it seems odd.

The serious issues with kernel panic and so on I think (hope) is limited to relatively few users/machines. I haven’t had a single instance. If that happened frequently on my new mac I would insist on a replacement as this would indicate faulty hardware unless it’s solely related to specific non-apple signed software.

I've been holding off an order until I hear that there is a resolution. But I've been thinking about ordering a unit without the 5700XT. Almost all of the chatter I hear is from the 5700XT and the white lines. Can anyone verify that the white line issue exists on the non-5700XT units?

There are 13 pages of posts. Perhaps it would be best if Apple stopped selling this configuration since people seem to keep buying it, only to be unhappy and exchange or return it. Pull it now and limit the number of machines Apple with have to replace when someone finally figures out what the problem is.

There are engineers all over the planet who think this machine will never be a success due to the poor cooling system. As they say the flaws could find a source in the fact that the components inside the case are continiously overheating. this will as well shorten the live span of the machine. And if this is the reason Apple is in big trouble because they have to come up with a new design of the inner working which can mean a long delay of reintroducing the machine. For now this is still theory but you never know....

Hi(Bonjour),

I think that the white line problem and the square corner issue are not related to the same cause as the loud fan. I see the white line once, but despite heavy compression job in Compressor, my fan is quiet. I own the 5700XT 16 Go GPU.

The fact the white line does not appear while playing games, with scaled resolution, when using bootcamp or when in restore mode might be a strong indication that the issue is just a software one (on the driver or OS).

Apart from that has been days I didn't see the line, the games are performing great, I use it to code and the compilation is pretty fast comparing with my i9 MacBook Pro.

I don't think it warrant a return if the most likely cause is not hardware. A perfect running machine would just become garbage which is detrimental to the environment, on top of that a new machine would have to be shipped from Foxconn, Shanghai creating even more pollution.

It seems to be wise to give them more time to find the issue and fix the likely cause, software.

How wonderful - I'm looking forward to your review. If any of the few others in here who like me had full system crashes kept their iMac - can you also please report back if the this 10.15.7 macOS Catalina update fixes that too? :-)

It appears to be too early to conclude that. The 5700XT and the CPU share a heat pipe, and it's pretty easy to imagine scenarios where one (particularly the 10-core i9) or the other (the GPU/graphics memory) — or both — fall into a race state that overwhelms the thermal dissipation hardware. Neither here nor else where online where this issue is being discussed do all the reports include load fans.

I realize it's a different kettle of dish than the 10-core i9 + 5700XT configuration of this year's model, but I rarely hear the fan in my 2017 27-inch iMac with the then top of the line config (quad-core i7 @ 4.2 GHz base clock speed, Radeon Pro 580/8 Gbyte). Disclaimer: in the summer months, I have a couple of very quiet circulation fans going at low speed, as well as an air purifier (the only louder than nearly silent fan) in the room with my desk.

Given experience with iMacs since 1998, I would discount these claims of "Apple doesn't know what it's doing with thermal design." I suspect Apple knows quite well how to dissipate heat from the 2012 - current iMac enclosure. Whether there's enough heat dissipated to insure more than the three years of reliable operation is another question: I just don't know. And that's why I will probably purchase a 2020 model if these graphics issues are resolved.