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Actually, it's not intrinsic to DisplayPort 1.2 that 4k displays must be driven with MST, it's just that for a long time the electronics to decode the full sign

Actually, it's not intrinsic to DisplayPort 1.2 that 4k displays must be driven with MST, it's just that for a long time the electronics to decode the full signal were not available, hence the hack. Starting with the Samsung U28D590D[1], many 4k displays use single stream transport on DP 1.2. Also, for 5k, you actually have to wait for DisplayPort 1.3 (if you want 60hz), because there's not enough bandwidth, multi stream transport or not. There's a neat bandwidth calculator at [2]. 4k is 11.94 GBit/s without overhead, 5k is 21.23 GBit/s. DisplayPort 1.2 and 1.3 are 17.28 Gbit/s and 25.92 Gbit/s respectively. This unfortunately means no 120hz 5k displays on even DP 1.3 without compression (which is supported). [1] http://www.pcper.com/reviews/Displays/Video-Perspective-Samsung-U28D590D-28-4K-Single-Stream-60-Hz-Monitor-Review http://www.pcper.com/reviews/Displays/Video-Perspective-Sams... [2]http://emsai.net/projects/widescreen/bandwidth/ http://emsai.net/projects/widescreen/bandwidth/

wlesieutre 12y ago
Oh, good to know. I'd assumed the MST screens were because they had to use it, but I guess I just jumped on the 4K train a few months before I should have...
nsxwolf 12y ago
So does that mean no 60Hz 5K displays for the 2013 Mac Pro?
- reitzensteinm 12y ago
  Correct. Thunderbolt 2 includes support for DP 1.2[1]. And in any case, only has 20 Gbit/s of bandwidth in total, which isn't enough for 5k even without taking overhead into account. Which makes this announcement quite strange. If this iMac doesn't support Thunderbolt 3 (or whatever standard Apple is planning), it'll never be usable as an external monitor. IMO, it would have been more Apple-y to launch this and refreshed Mac Pros simultaneously with TB 3, allowing Mac Pros to drive two (or more) 5k displays while the rest of the PC world is still tripping over 4k. But I guess this segment isn't a priority for them any more. http://en.wikipedia.org/wiki/Thunderbolt_%28interface%29#Thunderbolt_2 http://en.wikipedia.org/wiki/Thunderbolt_%28interface%29#Thu...
  - nsxwolf 12y ago
    Not even if they use 2 thunderbolt 2 channels to drive it?
    - reitzensteinm 12y ago
      The bandwidth would certainly be there, and there's precedent with monitors requiring dual HDMI to get to 60hz, but I'm not aware of the same thing being done with DisplayPort. With DisplayPort 1.3 now released, I'd be pretty surprised if manufacturers messed around with dual DP 1.2 inputs for displays like Dell's upcoming 5k. Such things are tolerated when there is no alternative, but when it's just a matter of requiring a new video card for a tenth the price of the high end display, that's the only sensible option. This is extreme early adopter tech after all. 5k is yesterday's 4k. And needless to say, if I'm speculating it's too messy for Dell, Apple won't touch it with a ten foot pole :) Still, stranger things have happened. If the demand turns out to be there, the products will follow - it's certainly technically possible.
      - nsxwolf 12y ago
        The 30" Cinema Display had 2 DVI connectors, which was nasty but necessary. So maybe Apple wouldn't be too disgusted by the thought of dual TB. But if DP 1.3 is around the corner, and dual TB would be an ugly hack that is mutually exclusive with the new standard, I could see them steering clear from that.
        pilif 12y ago
        >The 30" Cinema Display had 2 DVI connectors, which was nasty but necessary. not true. It has one DVI connector, albeit a dual-link one (the DVI connector supports two concurrent channels). Source: Me looking at the machine my 30" cinema display is connected to.
        nsxwolf 12y ago
        Huh, weird. Don't know why I thought that.
- wrboyce 12y ago
  According to a review[0] I read the new Dell 5k display has 2xDP1.2, so there is hope :) [0]: http://www.maximumpc.com/dells_5k_monitor_pre_reviewed_2014 http://www.maximumpc.com/dells_5k_monitor_pre_reviewed_2014

wlesieutre 12y ago

Oh, good to know. I'd assumed the MST screens were because they had to use it, but I guess I just jumped on the 4K train a few months before I should have...

nsxwolf 12y ago

So does that mean no 60Hz 5K displays for the 2013 Mac Pro?

reitzensteinm 12y ago
Correct. Thunderbolt 2 includes support for DP 1.2[1]. And in any case, only has 20 Gbit/s of bandwidth in total, which isn't enough for 5k even without taking overhead into account. Which makes this announcement quite strange. If this iMac doesn't support Thunderbolt 3 (or whatever standard Apple is planning), it'll never be usable as an external monitor. IMO, it would have been more Apple-y to launch this and refreshed Mac Pros simultaneously with TB 3, allowing Mac Pros to drive two (or more) 5k displays while the rest of the PC world is still tripping over 4k. But I guess this segment isn't a priority for them any more. http://en.wikipedia.org/wiki/Thunderbolt_%28interface%29#Thunderbolt_2 http://en.wikipedia.org/wiki/Thunderbolt_%28interface%29#Thu...
- nsxwolf 12y ago
  Not even if they use 2 thunderbolt 2 channels to drive it?
  - reitzensteinm 12y ago
    The bandwidth would certainly be there, and there's precedent with monitors requiring dual HDMI to get to 60hz, but I'm not aware of the same thing being done with DisplayPort. With DisplayPort 1.3 now released, I'd be pretty surprised if manufacturers messed around with dual DP 1.2 inputs for displays like Dell's upcoming 5k. Such things are tolerated when there is no alternative, but when it's just a matter of requiring a new video card for a tenth the price of the high end display, that's the only sensible option. This is extreme early adopter tech after all. 5k is yesterday's 4k. And needless to say, if I'm speculating it's too messy for Dell, Apple won't touch it with a ten foot pole :) Still, stranger things have happened. If the demand turns out to be there, the products will follow - it's certainly technically possible.
    - nsxwolf 12y ago
      The 30" Cinema Display had 2 DVI connectors, which was nasty but necessary. So maybe Apple wouldn't be too disgusted by the thought of dual TB. But if DP 1.3 is around the corner, and dual TB would be an ugly hack that is mutually exclusive with the new standard, I could see them steering clear from that.
      - pilif 12y ago
        >The 30" Cinema Display had 2 DVI connectors, which was nasty but necessary. not true. It has one DVI connector, albeit a dual-link one (the DVI connector supports two concurrent channels). Source: Me looking at the machine my 30" cinema display is connected to.
        nsxwolf 12y ago
        Huh, weird. Don't know why I thought that.
wrboyce 12y ago
According to a review[0] I read the new Dell 5k display has 2xDP1.2, so there is hope :) [0]: http://www.maximumpc.com/dells_5k_monitor_pre_reviewed_2014 http://www.maximumpc.com/dells_5k_monitor_pre_reviewed_2014