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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 w

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.

noahtallen 5y ago
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.
fotta 5y ago
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 :)
- owenwil 5y ago
  Whoops - you're right!
o_m 5y ago
They could have made it 90hz then
- notriddle 5y ago
  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.
  - o_m 5y ago
    A little Pro Motion would've fixed that
EugeneOZ 5y ago
They’ve could add a DisplayPort or HDMI 2.1 input to solve it.
shadowfacts 5y ago
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_limits_for_HDR_video https://en.wikipedia.org/wiki/DisplayPort#Refresh_frequency_...
- FireBeyond 5y ago
  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.

noahtallen 5y ago

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.

fotta 5y ago

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 :)

owenwil 5y ago
Whoops - you're right!

o_m 5y ago

They could have made it 90hz then

notriddle 5y ago
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.
- o_m 5y ago
  A little Pro Motion would've fixed that

EugeneOZ 5y ago

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

shadowfacts 5y ago

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_limits_for_HDR_video https://en.wikipedia.org/wiki/DisplayPort#Refresh_frequency_...

FireBeyond 5y ago
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.