
Update: 800圆00 has mysteriously appeared as the only other available resolution. never pulled apart before (first couple of Apple Discussions links) or if the LCD data cable was replaced entirely (Ask Different link)ĭoes anyone have any further insight into this problem? But this isn't applicable to those who encountered the issue on the iMac from when it was relatively new, i.e. One user has fixed it after a PSU and SSD install procedure caused snowy display, by reconnecting the LCD data cable. Setting the resolution to 2560x1440 using SwitchResX will allow the UI to appear as 1440p should, but the rendered resolution is still 720p (in other words, it looks like 720p at 0.5x scaling) Mid-2012 Retina MacBook Pro 15" connected to the Late 2012 iMac 27" in TDMīooting off of a live Ubuntu USB drive boots up with no display unless the nomodeset boot argument is used, which then allows Ubuntu to display at 720pĮxporting the EDID using SwitchResX shows that the EDID is not corrupt, and appears identical when exporting from the iMac itself and from another Mac when it is connected in TDM ( Pastebin) Also, it takes two presses of Command ⌘ + F2 to exit TDM. Brightness of the iMac can't be adjusted, and while its speakers are exposed as a sound output option in the host Mac, no sound from the host Mac plays through the iMac speakers. Using the iMac as a monitor for another Mac via Target Display Mode (TDM) works at the iMac's native 1440p resolution (ruling out internal LCD/data cable connection issue).Late 2009 iMac 27" in Target Display Mode works as an external display via Mini DisplayPort cable An external 1440p monitor connected to the iMac will work at its native resolution (ruling out GPU issue).Booting into Windows (Boot Camp, presumably) on the Mac.The following solutions are confirmed to not work: IMac boots at very low resolution (screen fell off and cables were pulled out, screen still works but only at 720p) Hey guys, I have a 27in 2013 imac, turned it on today, stuck on 720p for some reason.

Q: imac27 late2013 problem stuck on 1280x720 Q: 2560x1440 resolution not available on my new 27" imac Q: How can I set the 27" Imac to have full resolutions not 1280x720
