An unknown but growing number of iMac users are reporting display failures on their M1 iMacs, typically around two years after purchase.
Apple's 24-inch M1 iMac
Apple has had screen issues of various types before, and it's perhaps not surprising given the complexity of displays. But this new one has the extra sting that it appears to be mostly happening after the iMac is out of warranty.
The first reports, as spotted by Tom's Hardware, came in October 2023.
"Persistent horizontal lines appear on the screen [of a 24-inch iMac], which significantly hampers the usability and visual appeal of the device," wrote user latVm on Apple's discussion forum. "This problem arises without any physical damage, and despite the stationary nature of the device."
An example of the horizontal lines fault (Source: user latVm on Apple's discussion boards)
The reports of similar failures have continued, and it appears that users have been advised to pay for a screen replacement. One user who was told the same thing by Apple, claims to have taken his or her M1 iMac to a technician who subsequently puts the blame on a cable.
"The problem, apparently, lies in a cable that also powers the LCD, which is located on one of the tops of the screen," wrote user Jotap62, "and which, in order to be replaced, requires detaching the screen glass from the LCD itself, which is a very sensitive operation and almost impossible to carry out without damaging the LCD."
Reportedly, the cable "has to sustain a very high voltage (around 50V) to power the LCD," and after around two years, "it starts to burn out."
Apple does not include the iMac in its online repair cost estimator. Multiple affected users, however, have said they've been quoted between $650 and $700, which is around half the price of a new base model iMac.
If it's correct that the issue typically occurs after two years, it is out of Apple's regular warranty, but within the initial three years of AppleCare.
Beyond reported advice to users, Apple has not commented publicly on the issue.