I have a 2019 i9 iMac with an 8 GB Radeon Pro 580X running MacOS Monterey 12.6.8.
A few days ago I noticed a thin red vertical line ≈1 cm from the R bezel. Based on the closeup photo, it appears to be 1 pixel thick. It's intermittent, and moving windows around makes it go away. I've rebooted three times since it first appeared, but still occasionally see it.
Googling tells me that a permanent red line is a problem occasionally seen on Macs. But I couldn't find any reports of this appearing intermittently. I have two connected displays, and haven't seen it on either of them.
The Apple Hardware Test found no issues. I suppose the next step would be a PRAM + SMC reset, not because I know of any reason those should fix this, but rather since it doesn't hurt to try them.
My AppleCare+ is good through 2024, so I could wait and see if it becomes permanent. But it would be nice if this were a known issue with a simple fix.
The red line is the left of the two seen in the first two photos (the black vertical line to the right is supposed to be there—it's the window border). The thick black border on the right is the bezel.
A few days ago I noticed a thin red vertical line ≈1 cm from the R bezel. Based on the closeup photo, it appears to be 1 pixel thick. It's intermittent, and moving windows around makes it go away. I've rebooted three times since it first appeared, but still occasionally see it.
Googling tells me that a permanent red line is a problem occasionally seen on Macs. But I couldn't find any reports of this appearing intermittently. I have two connected displays, and haven't seen it on either of them.
The Apple Hardware Test found no issues. I suppose the next step would be a PRAM + SMC reset, not because I know of any reason those should fix this, but rather since it doesn't hurt to try them.
My AppleCare+ is good through 2024, so I could wait and see if it becomes permanent. But it would be nice if this were a known issue with a simple fix.
The red line is the left of the two seen in the first two photos (the black vertical line to the right is supposed to be there—it's the window border). The thick black border on the right is the bezel.
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