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5K2K at 120Hz with Mac Mini M4

Chancha said:
We need to wait for waydabber, the BetterDisplay dev, to test and comment on this. The 7680px width pipe limit has been there for so long it almost seems hardware bound. But then the above changes didn't look like it was possible to be changed via software either, so we will see.

But personally I won't hold high hopes, this is not only low priority for Apple but likely is indeed a hardware ceiling in the SoC display engine.
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Agreed. However virtual screens have been possible to create without the same limitations and apart from the performance degradation from the whole "stream a virtual screen to a real display" setup it works just fine. So I can't see why every single Mac to date would require this hard 8K framebuffer limit.

I would not be surprised that this is just an area that Apple is actively ignoring because it works acceptably on their 5K and 6K 16:9 screens. Hell, even 8K 16:9 would still allow for "looks like 3840x2160" scaling because it doesn't hit the horizontal resolution limit as fast as ultrawides do.
 
I've been on the beta since the first one and it's still broken. 165Hz is now selectable on more resolutions on my mac (M5 Pro) but it really isn't in reality: "feels like" it's capped at 100Hz or something (I'm comparing to other PCs and other macs I connect via the same cable).
HDR still isn't available (only on some resolutions, not all).
I already sent feedback to Apple, but don't know if this will ever be addressed.

Still wild that a cheap random chinese notebook with linux I have on my desk can run my ultrawide at any res + 165Hz + HDR without any issue and my 3500$ Macbook Pro can't..
Used to buy Apple products because they were the "just works" ones..
 
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andreeinprogress said:
I've been on the beta since the first one and it's still broken. 165Hz is now selectable on more resolutions on my mac (M5 Pro) but it really isn't in reality: "feels like" it's capped at 100Hz or something (I'm comparing to other PCs and other macs I connect via the same cable).
HDR still isn't available (only on some resolutions, not all).
I already sent feedback to Apple, but don't know if this will ever be addressed.

Still wild that a cheap random chinese notebook with linux I have on my desk can run my ultrawide at any res + 165Hz + HDR without any issue and my 3500$ Macbook Pro can't..
Used to buy Apple products because they were the "just works" ones..
Click to expand...
It definitely goes to 144Hz (the popular refresh rate test web page will show it) at least on an M4 mini. My monitor supports 4K@160Hz but macOS will only drive it to 144Hz, on the HDMI cable at least. Haven’t tried USB-C to DP yet. I also can’t get HDR to work even when forced.
 
QuarterSwede said:
It definitely goes to 144Hz (the popular refresh rate test web page will show it) at least on an M4 mini. My monitor supports 4K@160Hz but macOS will only drive it to 144Hz, on the HDMI cable at least. Haven’t tried USB-C to DP yet. I also can’t get HDR to work even when forced.
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The refresh rate issue is really weird, I can't quite explain it (therefore the "feels like" statement).

On my system (LG 5K2K ultrawide @ max 165Hz) macOS does report 165Hz (refresh rate tests too as you mentioned, the number is correct), but as soon as I plug in some other PC which can run at 165Hz the difference is really big, the 165Hz of macOS do not feel in any way as smooth as the 165Hz on linux for example.

I suspect (could be wrong, haven't got time to go deep into it) to be linked to how macOS is using (or failing to use) Display Stream Compression (DSC) right now to handle such high bandwits.
 
andreeinprogress said:
The refresh rate issue is really weird, I can't quite explain it (therefore the "feels like" statement).

On my system (LG 5K2K ultrawide @ max 165Hz) macOS does report 165Hz (refresh rate tests too as you mentioned, the number is correct), but as soon as I plug in some other PC which can run at 165Hz the difference is really big, the 165Hz of macOS do not feel in any way as smooth as the 165Hz on linux for example.

I suspect (could be wrong, haven't got time to go deep into it) to be linked to how macOS is using (or failing to use) Display Stream Compression (DSC) right now to handle such high bandwits.
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That does make sense. I have my monitor plugged into a Linux server as well and it is pretty smooth. It’s probably just how macOS handles buffering. The Linux box running Gnome 50 uses triple frame buffering so it’s extremely smooth.
 
I haven't tried MacOS 27 yet, but on Sequioa and Tahoe it's very clear that Displayport is better supported than HDMI. Which is insane when the only display output port found on Macs is HDMI.

I use my Samsung G95NC 7680x2160 superultrawide via my M2 Max or M5 Pro MBP's native HDMI port + USB-C -> DP 2.1 adapter in split screen mode. The display is run in Picture by Picture mode split into 21:9 + 11:9 / 5120x2160 + 2560x2160 displays.

This is what I see:
  • Displayport wakes up much, much faster than HDMI.
  • Displayport can handle oddball resolutions better. I can't get 120 Hz working on the 2560x2160 side via HDMI, but 3840x2160 or 5120x2160 works. With Displayport, 2560x2160 @ 120 Hz works fine. MacOS doesn't seem to know what to do with the odd 2560x2160 resolution.
  • Displayport is more likely to run at 10-bit RGB color. HDMI on my M5 Pro tends to default to 10-bit YCbCr 4:4:4 limited, but my M2 Max (running Sequioa) seems to pick up 10-bit RGB with the same setup. I need BetterDisplay to fix this on Tahoe.
  • Displayport is more likely to support high refresh rate + HiDPI scaling
  • For oddball resolutions, HiDPI scaling still might not work out of the box and you need to enable it with BetterDisplay.
MacOS is truly such a turd for external display handling. I really wish MacOS 27 would actually do something about all this, including removing that 8K framebuffer limit that severely hampers HiDPI scaling on ultra/superultrawides.
 
T'hain Esh Kelch said:
All Macs have Thunderbolt, which uses Displayport for video.
Click to expand...

I could be wrong, but my research led me to believe that when you plug a USB-C to DP cable into a "TB" port, the mac actually switches the port into a DP mode. The signalling on the cable is pure DP, as real as if the mac had big old DP jacks. So, Apple did a good job except that UHBR13.5 was not implemented on TB5 macs (only UHBR10 and 20).

Default colour depth is all over the place for me (M4 Pro mini, Tahoe) no matter DP or HDMI. I have 3 displays, and have to use BD to force RGB Full on all.
 
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