Over the past year and a half or so, some owners of the 24-inch iMac with the M1 chip have encountered horizontal lines abruptly appearing on the computer's screen. There are complaints about this issue across the Apple Support Community, MacRumors Forums, Reddit, iFixit Answers, and several other websites, but it is unclear how many customers are affected in total, or what the underlying cause of the problem is. Many affected users said the lines began appearing on the screen around 18 to 24 months after they purchased the iMac. As a result, the affected iMac units are often no longer covered by Apple's standard one-year warranty at the time the issue begins, unless the customer purchased extended AppleCare+ coverage. Some customers who contacted Apple about the issue said the company offered them an exemption, resulting in their iMac being repaired for free, but other customers said they had to pay for service. One symptom commonly mentioned is the top-right corner of the iMac becoming hot to the touch after the issue begins, but there is no confirmed cause. Given that these complaints have been continuously popping up for nearly two years now, there may be a hardware issue with this particular iMac model, which launched in May 2021. We have not seen widespread complaints about this issue affecting the iMac with the M3 chip, although that model was released less than a year ago. Apple offers service programs for some hardware issues, but it is unclear if it will ever launch one for this iMac issue. We have reached out to Apple for comment on this matter, and we will update this story if we receive a response.Related Roundup: iMacBuyer's Guide: iMac (Neutral)Related Forum: iMacThis article, "M1 iMac Owners Complain About Horizontal Lines Appearing on Screen" first appeared on MacRumors.comDiscuss this article in our forums