I have a BenQ EX3501R monitor connected by HDMI to my MacBook Pro, which is a Early 2015 model.

The issue being that OS X gets the resolutions completely wrong - the monitors native resolution is 3440x1440 but it switches it to 6720x3780!

Alt-clicking the 'Scaled' radio box does not list the correct resolution.

For further confusion, a Mid 2012 15' MacBook Pro connecting to the same monitor via the same HDMI cable works fine. The only notable difference is that one has a GeForce chip, where as mine is Intel Iris.

Both are running latest Mojave 10.14.1

any ideas of a way to proceed?

graphic info suggested resolution osx-info display-settings

  • what you did not tell us how does the picture looks like at 6720x3780!
    – Ruskes
    Dec 3, 2018 at 16:37
  • did it work on the 2015 before Mojave upgrade ?
    – Ruskes
    Dec 3, 2018 at 17:11
  • @Buscar웃 it rendered, but everything was tiny and pixelated. didn't look good. I got the monitor after i upgraded the OS X to Mojave Dec 9, 2018 at 19:27
  • Having the same issue with a dell u3818dw. Native resolution is 3,840 x 1,600 pixels but that option is not available (even with alt-click).
    – DocWatson
    Feb 27, 2019 at 13:40
  • Ultimately I restarted the 'dock' that I was using and the correct resolution appeared. If you're using an adapter or dock (which, it's a mac so of course you are), unhook it/power it off and back on.
    – DocWatson
    Feb 27, 2019 at 14:15

2 Answers 2


It might be the Monitor profile used by Mojave that needs repair.

Open the Color sync Utility in the Utility Folder

color sync utility

Verify you Monitor is showing correctly under devices.

Use the Profile First Aid.

  • you might be onto something, 53 profiles are needing repair, and on clicking Repair, it said only 2 were fixed. sigh. "The file is locked. Could not be fixed." Is there a way to run this as root? Dec 9, 2018 at 19:37

I had the same problem with DELL U3818DW. There is a chance that your graphics card doesn't support HDMI 2.0

NOTE: If you do not see 3840 x 1600 as an option: Check you graphics driver. Ensure you have the latest graphics drivers installed. Check your HDMI setting. U3818DW ships with HDMI 2.0 as default setting. If your graphics card only supports only HDMI 1.4, 3840 x 1600 will not appear in under the resolution table. Do the following to get 3840 x 1600 on the resolution table. From the Monitor OSD > Input Source On your current HDMI connection (e.g. HDMI1 or HDMI2), press and hold Confirm button for 8 seconds to switch monitor from HDMI 2.0 to HDMI 1.4.

Instuctions for DELL U3818DW

After doing the above in the monitor's settings (switching from HDMI 2.0 to HDMI 1.4) the issue was gone.

  • Thanks, I'll see if my monitor has equivalent settings Oct 8, 2019 at 15:42

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