Screen flickering 2nd Monitor at 75Hz with a certain resolution - Dual Monitor (MBP M4pro) #4485
Replies: 5 comments
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Can you show me an image of the refresh rate selector in the app and in System Settings for the problem display? Also, can you please attach the result of the following Terminal commands?
(note: if the string 2721 is not present in the second display's name, substitute it with something it has in its name) |
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Thank you for your help with this. 
I selected 75Hz for the terminal commands. Terminal command 1: Terminal command 2: 0 - 800x600 75Hz 10bpc |
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Well, the 59.95Hz in the app settings and 60Hz in system settings are not the same. The first one is a legacy NTSC refresh rate (shown separately) which System Settings does not expose - apparently the display does not like this. I am not sure why the 60Hz normal mode does not appear in the app's refresh rate list - which resolution are you using? It might not have a 60Hz variant. |
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Resolution is 85% scaled, with HiDPI on - 2176 x 1224. The issue only occurs with 75 Hz; there is no flicker at 60 Hz / 59.95 Hz. When 60 Hz is selected in the system menu, no flicker. If I select 59.95 Hz in the better display, it reverts to 75 Hz. I am trying to understand why the 75 Hz with 85% scaling is an issue. Thanks. |
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Hmm. Interesting. The 60Hz mode should present itself in the app menu I think (although this is not your issue). I don't know why the flickering issue presents itself at 75Hz - does this happen at all scaling levels? Scaling should not affect the actual output resolution so the flicker might somehow be related to some framebuffer scaling operation at the OS level maybe? |
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New user,
Dual Monitor - HiDPI (85% both monitors)
Monitor 1 - Dell U2719D (set as primary, 2560x1440, 75 Hz)
Monitor 2 - Dell S2721DS (2560x1440, 75 Hz)
The screen periodically flickers (once a minute or similar) on monitor 2.
Connection is MBP M4pro -> Caldigit TS4 -> Elgato Thunderbolt 3 Mini Dock -> Display Port (Monitor 1), HDMI (Monitor 2).
Monitor 2
If I set the refresh rate to 59.9 Hz on the Betterdisplay drop-down, it resets to 75Hz after some time, causing the flicker to return.
If I set the refresh rate to 59.9 Hz in the system settings, the issue disappears.
Any advice appreciated.
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