Re:My journey for dual displays with my M1 Pro Mac (2021)
by paulmd on Friday March 04, 2022 @11:45AM
(#30557107)
I have 3440x1440 and it works fine - I run 100 hz on my work MBP. Which is Intel, granted, but 3440x1440 is strictly less than 4k, and we don’t see an epidemic of people noticing that their 4k monitor is running at 30 hz on their M1 MBPs.
50 hz happens to be the limit of hdmi 1.4b (at 3440x1440), it sounds like somewhere in your chain you have something that is running at legacy speeds. Could be your dock, could be your monitor, could be an active adapter cable.
I’d start by making sure you’re running DisplayPort and not HDMI. HDMI is more or less a “legacy” port these days, as far as workstation usage is concerned. And unlike DP there is no embedded HDMI support in USB-C Alt Mode so any sort of USB-C to HDMI adapter needs an active converter - which may be your hdmi 1.4 bottleneck.
(note that the "passive" HDMI mode that full-size displayports offer - aka DP++ - is an optional part of the spec. It's so widely implemented on full-size ports that most people don't realize it's optional, but embedded DisplayPort implementations like eDP or USB-C Alt Mode, Thunderbolt, etc don't implement this feature.)
50 hz happens to be the limit of hdmi 1.4b (at 3440x1440), it sounds like somewhere in your chain you have something that is running at legacy speeds. Could be your dock, could be your monitor, could be an active adapter cable.
I’d start by making sure you’re running DisplayPort and not HDMI. HDMI is more or less a “legacy” port these days, as far as workstation usage is concerned. And unlike DP there is no embedded HDMI support in USB-C Alt Mode so any sort of USB-C to HDMI adapter needs an active converter - which may be your hdmi 1.4 bottleneck.
(note that the "passive" HDMI mode that full-size displayports offer - aka DP++ - is an optional part of the spec. It's so widely implemented on full-size ports that most people don't realize it's optional, but embedded DisplayPort implementations like eDP or USB-C Alt Mode, Thunderbolt, etc don't implement this feature.)