A small number of 2020 iMac owners report issues with the Mac’s AMD Radeon Pro 5700 XT GPU. A recent thread on the Apple Support Forums outlines a possible issue with the GPU that causes random lines to appear on the display.
The latest 27-inch iMac can be configured to include a Radeon Pro 5700 XT with 16GB of GDDR6 memory.
9to5Mac reports the original users that reported the issue says the 2020 iMac will randomly show lines across its display. While initially, the user believed it was due to “intensive work/heat” further testing revealed that was not the case.
I’ve just received my new iMac and noticed that from time to time a line glitch appears on my screen. It’s completely random, I thought it was related to intensive work/heat but sometimes even when the computer is idle I see the line on the screen.
The iMac is running fine, I ran all sorts of benchmarks for CPU/GPU and it’s all OK, but from time to time I see this annoying line on my screen.
Further research by another user shows the likely culprit for the issue is the 5700 XT GPU, it does not appear to affect the overall performance of the iMac.
Same problem with my iMac 2020, already appeared during the initial Mac setup and keeps flashing randomly since then. Searching through YouTube and google it seems this is a common problem with the 5700XT gpu that comes with it.
While it isn’t known how widespread the issue is, it is known to affect only the highest-end GPU configuration. It is likely a software issue and hopefully, Apple will roll out a solution soon.