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Comment by valine | Hacker News Reader

No 120hz listed in the tech specs, that’s gonna be jarring for people with a M1 macbook pro.

There's a good reason for this: Thunderbolt 4 doesn't have enough port bandwidth. TB4 can carry a max of 30Gbps but 5K @ 120hz is 32Gbps. There's no way Apple would do two cables for this, and the next gen of Thunderbolt is a while off, so the choice makes sense.

Doesn't display stream compression support higher bitrates? Also, I think thunberbolt 4 supports DisplayPort Alt Mode 2.0, which can handle up to like 80Gbps. But I guess that comes at the cost of attaching any other devices other than the monitor.

I think your math is off a bit. TB3/4 carries 40Gbps and 5k@120 is 53Gbps (5120 * 2880 * 120hz * 30bits/pixel). But your point still stands :)

Whoops - you're right!

They could have made it 90hz then

Running a program with fixed-rate 60hz (a lot of games) would cause judder. It's the same sort of reason they don't do 150% scaling; you want integer multiples of the "low-fi" version so that you can upscale without artifacting.

A little Pro Motion would've fixed that

They’ve could add a DisplayPort or HDMI 2.1 input to solve it.

DisplayPort 1.4 (which TB3/TB4 support as an alternate mode) has enough bandwidth for 5k at up to 144Hz using display stream compression (which Apple already uses for the Pro Display XDR): https://en.wikipedia.org/wiki/DisplayPort#Refresh_frequency_...

Whatever Apple is doing for the XDR (which I own) is not DSC, or not standard.

Because DSC has been broken ever since the Big Sur betas. Catalina supported 1.4 and DSC and my cheese grater Mac Pro happily drove 2x27" 4K monitors in HDR @ 144Hz.

Big Sur? Nope, you get 95Hz SDR or 60Hz HDR. If you set the monitors to DP1.2 you get 120Hz SDR.

I hardly notice when switching between my M1Pro monitor and larger 27" monitor. Sure my monitor do support 144Hz, but im running it at 60Hz... because docking station

There is a world of difference between 60 Hz and 144 Hz, though. I don’t think I can go back to anything less than 120.

Yeah it feels horrible now.

When I got my iPhone 13 pro it cost me an M1 iPad and a 14” MBP because everything felt horrible afterwards.

I disagree completely. My main monitor is at 144hz, and it's very jarring to switch to my (slightly older) MBP running at 60hz. Not having high refresh rate means this new monitor won't ever be on my short list.

I feel that while changing from 30hz to 60hz and the latter feels smooth (enough). Never used a higher refresh rate device but wonder how much more can this keep going and humans noticing.

Having used displays from 30Hz to 300Hz, I believe 120Hz vs 60Hz is easily noticeable for anyone who is aware of the differences. Higher than that is a steep point of diminishing returns in my experience.

I imagine things will get to the imperceptible range around ~500hz but diminishing returns apply. 60 to 120 is a bigger deal than 120 to 480.

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