Help Needed - MacBook Refresh Issue

[ChaosAngel]

I have a MacBook Pro 16-inch with the Radeon 5500M.

I connect to two 4K Dell Monitors via a TB3 > Dual-Display Port adapter. I have used this adapter for years (with previous MacBook's) and never had an issue.

Everything was working as designed until last week, when my Mac suddenly refused to deliver 60Hz to both displays. One display is 60Hz, the other falls back to 30Hz.

I have tried everything to get the monitors back to 60Hz and have confirmed the issue is the Mac, no the adapter (used a different adapter and even two different Dell monitors).

How can I over-write the refresh rate within macOS?

 

[matram]

Have you tried restarting your MBP, I know it sounds silly, but there seems to be different issues with the GPU drivers. Restarting, seems to get the GPU back to normal again.

 

[ChaosAngel]

Have you tried restarting your MBP, I know it sounds silly, but there seems to be different issues with the GPU drivers. Restarting, seems to get the GPU back to normal again.

Yep, no luck. I've also tried an NVRAM reset (long shot). Still locked at 30Hz on one display.

Is there anyway to get macOS to provide more detail regarding display settings. System Preferences is very simple, with no ability to force specific settings.

 

[gjr74]

I have the same issue! Same Mac as yours, and a Dell U2718Q. When I have the MacBook open and connected, both screens are at 60hz, then when I close the MacBook (clamshell mode), the Dell drops to 30hz. Very annoying. Connected with Anker Thunderbolt to HDMI, rated for 60hz. Wondering if I should buy a Thunderbolt to Display Port and see if that helps.