17 inch iMac resolution 1280x720

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Level 1

8 points

17 inch iMac resolution 1280x720

I have a 17 inch 2012 (Late) iMac (3.4Ghz) (13,2) with Nvidia GeForce 680MX. A few days ago, I noticed the resolution was not set to native 2560x1440, so I went into System Preferences to change it back and saw that the only available resolution is 1280x720. I have recently upgraded to Mojave, but I have had no resolution issues since the upgrade until this happened.

I have tried using a variety of EDID tools to dump the display settings as well as try to update them but to no avail. The system only allows 1280x720 scaled. It is the only entry available, other than 800x600 if I press option while selecting the Scaled radio button. There is no native resolution option.

I have gone so far as to install Windows using Bootcamp, to see what Windows detects and Windows sees only 1280x720 as well.

I have reset NVRAM and SMC etc. dozens of times while troubleshooting this.

I have also tried SwitchResX to no avail, it seems to go native but all looks pixelated.

If anyone has any clues, or a sample EDID file from a working Late 2012 iMac with my config, or SwitchResX settings, or simply confirming some hardware problem or known issue, it would be very helpful.

I have searched and search Google and see some references to this issue with various outcomes, but nothing concrete.

Thanks,

Mark.

iMac, macOS Mojave (10.14)

Posted on Nov 4, 2018 12:25 AM

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Answer 1

rkaufmann87

Level 10

148,458 points

Nov 4, 2018 7:46 AM in response to m.a.n.r.

I had no idea what you had, however lets see if we can figure out the problem. Please do the following.

Please post an EtreCheck report of your system and we can look for any obvious issues. Please click the link, download and run the free version of the app and then post the complete report it produces as your reply to this message.

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Answer 2

m.a.n.r. Author

Level 1

8 points

Nov 4, 2018 10:02 AM in response to m.a.n.r.

Dialabrain: is there any way you can paste the contents of your the files in the overrides folder in /system/library/displays/contents/resources/overrides (can’t remember exact path off top of my head), that ends in 005. Vendor folder is 610 if it’s same late 2012 machine as mine.

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Answer 3

dialabrain

Level 10

135,827 points

Nov 4, 2018 9:49 AM in response to m.a.n.r.

It might be worthwhile running the AHT if you haven't already. Although I've read it's not great at finding GPU issues.

How to use Apple Hardware Test on your Mac - Apple Support

Personally I think if a clean install didn't fix things it's probably a hardware issue. I happen to have a late 2012 27" iMac running Mojave without a problem.

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Answer 4

rkaufmann87

Level 10

148,458 points

Nov 4, 2018 7:28 AM in response to m.a.n.r.

Mark,

17" iMacs have not been made in about 15 years. I suspect you first need to learn what you have first and then let us know exactly how you attempting to change the display resolution in Mac OS.

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Answer 5

rkaufmann87

Level 10

148,458 points

Nov 4, 2018 9:24 AM in response to m.a.n.r.

You (or someone that has access) did a hard shutdown recently. Also, I don't see any evidence of a backup plan, this is guarantee of losing the data when your HD fails which they all do at some point.

Next, I don't see any applications installed. This seems a bit odd, did you include the complete report? In addition, it's wise to run report after the computer has been running for a day or longer, your system has only been up an hour.

Finally, questions for you...

Do you have any antivirus, cleaning, or any other third party "maintenance" apps installed?

What third party applications do you have installed?

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Answer 6

m.a.n.r. Author

Level 1

8 points

Nov 4, 2018 9:35 AM in response to rkaufmann87

As I mentioned, this is a brand new fresh install, done minutes ago on the bare system. The only 3rd party app on it is EtreCheck. Of course I have backups - I have backups up the wazoo, local on network, time machine, online sync etc. I'm a developer, I know how to keep source safe. This is a brand new install, I'm not here to discuss backup strategies.

If anyone else out there has actual experience with EDID overrides or this specific issue, please let me now.

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Answer 7

m.a.n.r. Author

Level 1

8 points

Nov 4, 2018 9:57 AM in response to dialabrain

Hi there, I think you are right, I actually ran that test a couple of days ago and it found no issues.

I also installed windows and it saw 1280x720 as well. I’m not sure what internal connector this mac uses for the built in display to from card to monitor, I’m wondering if somethings wrong with it. Or if it’s d-dvi and only one channel is working. I’m not even sure if this one is d-dvi.

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