You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

2019 MacBook Pro w/ Radeon Pro 555X + 4K 120 Hz external monitor not working

  • Attempting to output 4K (3840 x 2160) at 120 Hz results in a blank screen.
  • 4K at 60 Hz works
  • Outputting a smaller, "low resolution" resolution less than 4K (e.g. 3360 x 1890) at 120 Hz works, but is obviously not ideal due to not matching the monitor's native resolution.
  • I've tried all four USB-C ports on the MBP


How can I get 4K + 120 Hz to work?


To get to the dialog below: option + click on "Scaled", enable "Show low resolution modes". Select resolution + refresh rate from the dropdown selector.



macOS 10.15.6 (19G2021)


MacBook Pro (15-inch, 2019)

2.4 GHz 8-Core Intel Core i9

32 GB 2400 MHz DDR4

Radeon Pro 555X 4 GB

Intel UHD Graphics 630 1536 MB


Monitor: Acer XB273K


Cable: USB C to DisplayPort Cable 8K 60Hz, Maxonar 6.6FT/2M (4K 60Hz 144Hz 120Hz 2K 240Hz) VESA Certified 32.4Gbps Type-C Thunderbolt 3 to DP 1.4 HBR3 Alt Mode Video Adapter for MacBook Pro/iPad Pro, XPS 15

https://www.amazon.com/gp/product/B08B3XNZGS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1




Posted on Sep 14, 2020 9:18 AM

Reply
Question marked as Top-ranking reply

Posted on Sep 14, 2020 10:01 AM

Your Mac supports a maximum resolution up to 5120x2880 at 60 Hz at over a billion colors on up to two external displays or up to 4096x2304 resolution at 60 Hz at over a billion colors on up to four external displays via Thunderbolt 3 (USB-C).


Support for 4K @ 120 Hz is not listed.

Similar questions

2 replies

2019 MacBook Pro w/ Radeon Pro 555X + 4K 120 Hz external monitor not working

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.