Graphical Glitches Plaguing Some 2020 iMac Owners With Radeon Pro 5700 XT GPU
Apple in August refreshed the 2020 iMac lineup with a new 27-inch model that's equipped with 10th-generation Intel processors, more RAM, more SSD settings, and faster AMD GPUs.

Unfortunately, some new Mac owners have been running into problems with their machines and have been reporting ongoing glitching with the graphics. There's a 57-page thread on the MacRumors forums filled with complaints dating back to August, suggesting this is a problem that's been impacting iMac owners since the new Macs came out.
Based on a poll, a good number of iMac owners who have the higher-end 5700XT GPU are seeing a white horizontal line flicker across the display on occasion, but the problem does not seem to impact all users.
MacRumors reader
torifile describes the issue:
I got my 2020 iMac Thursday night. It's as fast as expected and gorgeous. Last night I thought I saw, out of the corner of my eye, a horizontal white line flash mid-way up the screen. It was really fleeting and I thought I was just seeing things. This morning, I saw the same thing. The computer isn't running hot or anything. iStat Menus has all the cores untaxed. I recall having this same problem with my MBP 13" (2019) with an earlier version of macOS (I can't remember if it was a late Mojave build or an early Catalina) and it was cleared up with a software update.
The white line described by those affected appears to flash across the screen at random intervals throughout the day, and there are some other seemingly related graphical issues that iMac owners have run into. Some users have reported being able to remedy the problem by choosing a scaled resolution other than the default, but that's not an ideal longterm solution.
It's not clear if the issue that iMac owners are experiencing is hardware or software based, but Apple has not yet implemented a fix for the problem.
Popular Stories
iOS 26 was released last month, but the software train never stops, and iOS 26.1 beta testing is already underway. So far, iOS 26.1 makes both Apple Intelligence and Live Translation on compatible AirPods available in additional languages, and it includes some other minor changes across the Apple Music, Calendar, Photos, Clock, and Safari apps.
More features and changes will follow in future ...
Apple plans to cut production of the iPhone Air amid underwhelming sales performance, Japan's Mizuho Securities believes (via The Elec).
The Japanese investment banking and securities firm claims that the iPhone 17 Pro and iPhone 17 Pro Max are seeing higher sales than their predecessors during the same period last year, while the standard iPhone 17 is a major success, performing...
With the fourth betas of iOS 26.1, iPadOS 26.1, and macOS 26.1, Apple has introduced a new setting that's designed to allow users to customize the look of Liquid Glass.
The toggle lets users select from a clear look for Liquid Glass, or a tinted look. Clear is the current Liquid Glass design, which is more transparent and shows the background underneath buttons, bars, and menus, while tinted ...
Apple's software engineers continue to internally test iOS 26.0.2, according to MacRumors logs, which have been a reliable indicator of upcoming iOS versions.
iOS 26.0.2 will be a minor update that addresses bugs and/or security vulnerabilities, but we do not know any specific details yet.
The update will likely be released by the end of next week.
Last month, Apple released iOS 26.0.1,...
iOS 26.4 is expected to introduce a revamped version of Siri powered by Apple Intelligence, but not everyone is satisfied with how well it works.
In his Power On newsletter today, Bloomberg's Mark Gurman said some of Apple's software engineers have "concerns" about the overhauled Siri's performance. However, he did not provide any specific details about the shortcomings.
iOS 26.4 will...
While the new iPad Pro's headline feature is the M5 chip, the device has some other changes, including N1 and C1X chips, faster storage speeds, and more.
With the M5 chip, the new iPad Pro has up to a 20% faster CPU and up to a 40% faster GPU compared to the previous model with the M4 chip, according to Geekbench 6 results. Keep in mind that 256GB and 512GB configurations have a 9-core CPU,...
Apple on Wednesday updated the 14-inch MacBook Pro, iPad Pro, and Vision Pro with its next-generation M5 chip, but previous rumors have indicated that the company still plans to announce at least a few additional products before the end of the year.
The following Apple products have at one point been rumored to be updated in 2025, although it is unclear if the timeframe for any of them has...
Apple plans to launch MacBook Air models equipped with the new M5 chip in spring 2026, according to Bloomberg's Mark Gurman. Apple is also working on M5 Pro and M5 Max MacBook Pro models that will come early in the year.
Neither the MacBook Pro models nor the MacBook Air models are expected to get design changes, with Apple focusing on simple chip upgrades. In the case of the MacBook Pro, a m...
Apple on Wednesday updated the 14-inch MacBook Pro base model with an M5 chip, and there are two key storage-related upgrades beyond that chip bump.
First, Apple says the new 14-inch MacBook Pro offers up to 2× faster SSD performance than the equivalent previous-generation model, so read and write speeds should get a significant boost. Apple says it is using "the latest storage technology," ...