It seems that some models of the 2020 27 "iMacs launched in August and equipped with the most prestigious GPU, the AMD Radeon Pro 5700 XT, have a bug attributable to the GPU: every now and then some lines appear completely randomly on the screen. come from users who have equipped the AMD card with 16 GB of GDDR6 memory, however it has not yet been able to identify other elements that allow to identify more precisely the nature of the problem.
For example, it does not seem a matter of overheating due to too intense workload. The lines also appear when the computer is idle or doing light tasks, such as web browsing. Even running various benchmarks and performance tests the system seems perfectly healthy. Which is good news – not that it makes the problem any less annoying, of course, but at least you can continue to use it normally.
It is not known how many owners of this particular iMac configuration are afflicted by the problem, however it could be a simple bug in the drivers that can be solved with a future update. The hardware defect (maybe even just the connector cables) could mean much greater hassle for the owners, but it seems a less likely hypothesis. For the moment, however, Apple has not yet expressed itself on the matter.