I own a:

  • LG Ergo 34WN780 - Ultrawide QHD Monitor - 34 inch
  • MacBook Pro (15-inch, 2019)
  • StarTech USB-C naar DisplayPort cable 1,8 metres

The monitor supports 75hz, but I can only configure it up to 60hz (3440x1440).

I've also tried to use the cscreen utility from terminal, but if I set:

cscreen -d 32 -x 3440 -y 1440 -r 75 -s 2

the monitor turns to 30hz for some reason, so it's decreasing (although I passed -r 75).

What could be the issue?

Update: I found this on some forum, by someone that bought my same exact monitor: if anyone can confirm would be great:

" just bought this monitor a few days ago and thought I would share some tips for Mac users. If you have a macbook pro I highly recommend that you also buy a display port 1.4 to usb c / lightening cable to use with this monitor. The included hdmi cable (or any other I've tried) will not get you the full 75hz refresh rate on 3440 x 1440. Also the display port cable produces a cleaner overall image + text. Through hdmi... it was really bad. I mean to the point where it was nauseating to read text on my text editor."

  • Is the mac limited to 60Hz? Seems like this has been addressed in previous posts.
    – Solar Mike
    Commented Feb 28, 2021 at 7:46
  • @SolarMike which posts? Are you sure you are referring to Hz for external monitor? (not the Macbook monitor)
    – aneuryzm
    Commented Feb 28, 2021 at 8:25
  • I said mac and I meant mac... other posts pointed out it had a 60Hz limit, and those posts were recent to, so a quick search should find them.
    – Solar Mike
    Commented Feb 28, 2021 at 8:27
  • @SolarMike Great, you meant mac then. I did a search of a couple of hours yesterday but I could not find a post/Apple doc specifying the Hz limit for external monitors for a Macbook (via DisplayPort). Maybe you can help? ;)
    – aneuryzm
    Commented Feb 28, 2021 at 8:31
  • 1
    I have just googled for myself, and I have to agree with @aneuryzm that the info is very limited and unclear. Some say they were able to get higher refresh rates than 60Hz, others didn't. I would double check the cable and try all ports. Apple only talks about 60Hz and nothing else.
    – X_841
    Commented Feb 28, 2021 at 8:39

1 Answer 1


I was able to get a full 75 Hz refresh rate on 3440 x 1440 with:

enter image description here

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