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

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.

Thanks for sharing. It was my first iMac ever so to be honest the loud fans did not bother me much as I was also running Windows in Parallels, but I do care about the rumors I've read that such iMac design with that massive hardware is bound to fry the circuits within a few years. I have no clue if there is any truth to that, but I would like my maxed-out iMac to last about 10 years.

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.

I don't think Apple is naive, many countries have very different rules of consumer protection, such here in NZ under the Consumer Guarantee Act, where the warranty has to be extended automatically based on the brand reputation, price paid and expectation of its economic lifespan which for computers are up to 7 years. So it is very easy to get a repair / replacement if the iMac goes bust after 3 or 4 years with no questions asked such happened a few times with two old macbooks of mine.

Everyone is bound to have to reply to someone in order to post. So, to quote from the link to MacRumors, if for no other reason than not to have to link back:

"... fixes a bug that could prevent files from syncing through iCloud Drive, and most notably for new iMac owners, it fixes an issue that was causing a small white flashing line to appear on machines equipped with the Radeon Pro 5700 XT."

https://www.macrumors.com/2020/09/24/apple-releases-macos-catalina-10-15-7/

If so, then I'm on my way to purhse what I was going to purchase before this thread. Wait and see.

Just to be clear - so you’re saying there’s no point buying Apple Care for an iMac if you live in NZ like I do? Because as New Zealanders we can just rely on the Consumers Guarantees Act if a repair is necessary for an iMac that has been purchased within a 7 year time frame? Are you sure about that?

In most cases it does not worth it.

Here you can find more information about extended warranty:

https://www.consumer.org.nz/articles/extended-warranties

Here you can find the reasonable lifespan for laptop and computers are 5 years for most of them, but because apple is a reputable brand and offer premium devices at premium price you can expect more than that.

https://www.consumer.org.nz/articles/appliance-life-expectancy

I hope it helps,

Regards

If you're only getting AppleCare(+) to cover hardware issues, it sounds as though it's probably not worth it in countries with such legal coverage. AppleCare+, however does cover accidental damage, which may or may not be covered under home and contents policies.

And I believe only AppleCare(+) covers tech support.

So, yes, the new update to MacOS 10.15.7 has completely got rid of the white line issue... so, yes, it was a software fault as everyone expected.

But, does anyone find they're missing their white lines now they're gone? My Mac used to be special, and now it's just the same as all the rest.

Mate, you‘re right.

I’m thinking about bringing the iMac back, because there are no white lines anymore. Hope to get another one with the old software.

Somehow it isn‘t the same... You guys think I can open it up, straight in the Apple Store to check if the Specialist and me can reproduce them? Would be epic.

"My Mac used to be special, and now it's just the same as all the rest."

Ahh... Do you mean that your special Mac was special because almost everyone else had the same special problem with their 2020 iMac? Sometimes, "special" is not special at all. At least, I can go ahead with MY purchase without belonging to a special group having consistent, irritating problems. Such "special" I neither wanted ~ needed.

What? You mean they prioritized the solution for the more obvious and annoying issue?

Disclaimer: Based on the reports of a solution to the line glitch, I ordered an i9/5700XT from Apple. We'll see if the corner glitch annoys me enough to return it, though I doubt it will, since I use dark mode 24 x 7.