d7d19285f0bd48

macrumors member
Original poster
Sep 13, 2020
36
37
Quick question. According to Apple, the MBP2019/5500M can drive dual 6k monitors at 6016x3384 pixels or quad 4096x2304. Fairly straightforward. But where do "X.5k" ultra wide monitors fall?
  • 6k - 6016x3384 -> 20,358,144 pixels
  • 5k - 5120x2880 -> 14,745,600 pixels
  • 4k - 4096x2304 -> 09,437,184 pixels
So if I am running....
  • 2x 6k -> 40,716,288 pixels.
  • 4x 4k -> 37,748,736 pixels.
What happens if I run a "5.5k" ultra wide? Can I run quad monitors?
  • 1x "5.5k" -> 5120x1440 -> 07,372,800 pixels
  • 2x "5.5k" -> 5120x1440 -> 14,745,600 pixels
  • 3x "5.5k" -> 5120x1440 -> 22,118,400 pixels
  • 4x "5.5k" -> 5120x1440 -> 29,491,200 pixels
Which is ultimately results in ~21% few pixels being driven compared to quad 4k monitors.
Thanks.
 

ha1o2surfer

macrumors 6502
Sep 24, 2013
407
39
Quick question. According to Apple, the MBP2019/5500M can drive dual 6k monitors at 6016x3384 pixels or quad 4096x2304. Fairly straightforward. But where do "X.5k" ultra wide monitors fall?
  • 6k - 6016x3384 -> 20,358,144 pixels
  • 5k - 5120x2880 -> 14,745,600 pixels
  • 4k - 4096x2304 -> 09,437,184 pixels
So if I am running....
  • 2x 6k -> 40,716,288 pixels.
  • 4x 4k -> 37,748,736 pixels.
What happens if I run a "5.5k" ultra wide? Can I run quad monitors?
  • 1x "5.5k" -> 5120x1440 -> 07,372,800 pixels
  • 2x "5.5k" -> 5120x1440 -> 14,745,600 pixels
  • 3x "5.5k" -> 5120x1440 -> 22,118,400 pixels
  • 4x "5.5k" -> 5120x1440 -> 29,491,200 pixels
Which is ultimately results in ~21% few pixels being driven compared to quad 4k monitors.
Thanks.


I don't see why it can't run 2 6k monitors and a couple 4k monitors. I don't why it wouldn't be possible. One of those 6k monitors may run at 30hz due to bandwidth limitations on the (right) side ports? I forget which set of ports Apple recommends for the XDR monitor.

That's above 100gbps of display data bandwidth, holy S*** lol

a SINGLE Pro XDR uses more bandwidth at 10bit 60hz then a 4k monitor at 120hz lol


you may have some issues if an app is swapping its video memory between the intel card and the AMD card. I recommend a cold boot when connecting to these monitors lol
 

d7d19285f0bd48

macrumors member
Original poster
Sep 13, 2020
36
37
Thanks. Might just order 4x monitors and see what happens. Can always facilitate a return. 🤷🏼‍♂️

Also thinking of going the eGPU route to use as a dock, if I can find one with the required compliment of ports. Like a eGPU with a built in Caldigit TS3 plus. Too much to ask???

Not doing anything crazy. Mostly analytics and GIS type stuff.
 

joevt

macrumors 68040
Jun 21, 2012
3,324
1,527
If the two 6K displays don't use DSC then they will use up all four available DisplayPort connections (two per side). The AGDCDiagnose command will show what type of connection is being used.

If the 6K displays use DSC (which they should since the 5500M supports it), you can connect both displays to the same side (one Thunderbolt controller). In that case, it's possible that two more displays could be connected (unless the drivers don't allow it or there's a limit in the hardware related to number of pixels or number of pixels per second or ability to do DSC on two 6K displays).

I don't think anyone's tried 30 Hz on the XDR (it's not a built-in timing, so you would have to add an override - you can use SwitchResX to try that).

5120x1440 is less pixels than 4K, so there shouldn't be a problem connecting four of them with your late model AMD dGPU. Macs using only older Intel iGPUs can't do wider than 4K. Coffee Lake and Kaby Lake iGPUs can do 5120 width but only with Big Sur. Ice Lake iGPU can do 5120 width in Catalina. AMD dGPUs from 2015 or earlier have garbled pixels with 5K width, even in Big Sur.

You don't need Thunderbolt from an eGPU for the XDR or the latest UltraFine 4K and 5K displays (5K can do only 4K without Thunderbolt because it requires two DisplayPort connections to get 5K). You'll want a method to pass USB 2.0+USB-C to the display for brightness control, audio, presets, etc. One method known to work with the XDR is the Belkin Charge and Sync cable.
 

ha1o2surfer

macrumors 6502
Sep 24, 2013
407
39
you're right its only 47Hz. So maybe the 4k displays would use 30hz? I assume they support DSC too
 

joevt

macrumors 68040
Jun 21, 2012
3,324
1,527
you're right its only 47Hz. So maybe the 4k displays would use 30hz? I assume they support DSC too
Most 4K displays do not use DSC. I don't think there are any 5K displays that use DSC.
There are some recent high refresh rate 4K gaming displays that use DSC.
Doesn't matter since 4K 60Hz doesn't require DSC and DSC would not help this situation.

If you were running Windows, you could connect a DisplayPort 1.4 MST hub and connect two 4K 60Hz displays to that. The input to the hub would be DSC otherwise two 4K displays could not be supported. The hub can convert 4-lane HBR3 DSC MST to two 4-lane HBR2 SST. MST can allow 2 or more displays from a single DisplayPort port. A GPU can support a limited number of displays. MST does not add to the limit except in the case where a GPU has fewer ports than the limit. macOS doesn't support MST for multiple displays.
 

d7d19285f0bd48

macrumors member
Original poster
Sep 13, 2020
36
37
So just so I am clear, I should be able to run 4x Dell U4919DW UltraSharp 49" monitors which run at 5120x1440 as each monitor supports DisplayPort 1.4 (which has DSC as part of the specification) via their DisplayPort connector or via the USB-C connector which supports also DisplayPort 1.4/alt mode by hooking them each up to one of the USB-C/Thunderbolt 3 ports on the MBP?

OR

I should be able to run 2x monitors via a Thunderbolt 3 dock that has dual DisplayPort 1.4 outputs by hooking the dock up to a single USB-C/Thunderbolt 3 port on the MBP? Such as the WAVELINK 8k Thunderbolt 3 Dock with DisplayPort 1.4?

Thanks!
 

joevt

macrumors 68040
Jun 21, 2012
3,324
1,527
So just so I am clear, I should be able to run 4x Dell U4919DW UltraSharp 49" monitors which run at 5120x1440 as each monitor supports DisplayPort 1.4 (which has DSC as part of the specification) via their DisplayPort connector or via the USB-C connector which supports also DisplayPort 1.4/alt mode by hooking them each up to one of the USB-C/Thunderbolt 3 ports on the MBP?
Yes. Only recent DisplayPort 1.4 displays support DSC. Older DisplayPort 1.4 displays do not support DSC. DSC is not needed for 5120x1440.
I don't know why the Dell supports DisplayPort 1.4 since it doesn't support high refresh, daisy chaining, HDR, or USB 3.0 over USB-C (except the manual says it supports only 8bpc from USB-C which implies that it is using only two lanes of DisplayPort 1.4 which would all for USB 3.x. over DisplayPort but the same line says only USB 2.0 is supported).

OR
I should be able to run 2x monitors via a Thunderbolt 3 dock that has dual DisplayPort 1.4 outputs by hooking the dock up to a single USB-C/Thunderbolt 3 port on the MBP? Such as the WAVELINK 8k Thunderbolt 3 Dock with DisplayPort 1.4?
Only if the displays are using HBR2 which should be true for 5120x1440 10bpc. In that case any Thunderbolt 3 dock (Alpine Ridge or Titan Ridge, DisplayPort 1.2 or DisplayPort 1.4) should work.
 

d7d19285f0bd48

macrumors member
Original poster
Sep 13, 2020
36
37
Yes. Only recent DisplayPort 1.4 displays support DSC. Older DisplayPort 1.4 displays do not support DSC. DSC is not needed for 5120x1440.
I don't know why the Dell supports DisplayPort 1.4 since it doesn't support high refresh, daisy chaining, HDR, or USB 3.0 over USB-C (except the manual says it supports only 8bpc from USB-C which implies that it is using only two lanes of DisplayPort 1.4 which would all for USB 3.x. over DisplayPort but the same line says only USB 2.0 is supported).


Only if the displays are using HBR2 which should be true for 5120x1440 10bpc. In that case any Thunderbolt 3 dock (Alpine Ridge or Titan Ridge, DisplayPort 1.2 or DisplayPort 1.4) should work.

Just to follow up since you seem exceedingly knowledgeable on the subject.
(Then again, you are an anonymous internet person......)

The Dell U4919DW supports an input of 1x DisplayPort 1.4 at 10-bit color at 60Hz. BUT the manual states it works over Display 1.2 as well. Which only supports HBR2 over 4 lanes. So in theory a docking station with 8x HBR2 via 2 Displayport connections (4 ea) should work.

The WAVLINK 8K Thunderbolt 3 Docking Station which claims to support 2x 4K or 1x 8K has the JHL7440 Thunderbolt 3 Controller which is part of the "Titan Ridge" line which Intel claims supports 8 HBR2 or 4 HBR3.

So in theory I should be able to go.....

2019 MacBook Pro

ThunderBolt 3 Cable

-------- WAVLINK Dock-------
↓ | ↓
Display Port 1.4 Cable | DisplayPort 1.4 Cable
↓ | ↓
Dell UltraSharp U4919DW | Dell UltraSharp U4919DW
(5120x1440 @ 60Hz) | (5120x1440 @ 60Hz)

In any event, I am just going to buy a setup and see what happens. Just trying to pick/choose to mitigate returns. Worst comes to worst, will just roll with 2x USB-C+DisplayPort docks (one to each monitor) and go side-by-side as 4x displays in MacOS.
 

joevt

macrumors 68040
Jun 21, 2012
3,324
1,527
Just to follow up since you seem exceedingly knowledgeable on the subject.
(Then again, you are an anonymous internet person......)

The Dell U4919DW supports an input of 1x DisplayPort 1.4 at 10-bit color at 60Hz. BUT the manual states it works over Display 1.2 as well. Which only supports HBR2 over 4 lanes. So in theory a docking station with 8x HBR2 via 2 Displayport connections (4 ea) should work.

The WAVLINK 8K Thunderbolt 3 Docking Station which claims to support 2x 4K or 1x 8K has the JHL7440 Thunderbolt 3 Controller which is part of the "Titan Ridge" line which Intel claims supports 8 HBR2 or 4 HBR3.

So in theory I should be able to go.....

2019 MacBook Pro

ThunderBolt 3 Cable

-------- WAVLINK Dock-------
↓ | ↓
Display Port 1.4 Cable | DisplayPort 1.4 Cable
↓ | ↓
Dell UltraSharp U4919DW | Dell UltraSharp U4919DW
(5120x1440 @ 60Hz) | (5120x1440 @ 60Hz)

In any event, I am just going to buy a setup and see what happens. Just trying to pick/choose to mitigate returns. Worst comes to worst, will just roll with 2x USB-C+DisplayPort docks (one to each monitor) and go side-by-side as 4x displays in MacOS.
Yes, 5120x1440 is fewer pixels than 4K so of course it should work with DisplayPort 1.2. I'm not sure what the Dell gets from supporting DisplayPort 1.4. HDR? DSC? YCbCr 4:2:0? This display needs none of those. The display supports HDCP 2.2 which comes from DisplayPort 1.3 - that's probably why DisplayPort 1.4 is supported.

If the display connects with HBR3, then a DisplayPort 1.4 cable will be required. However in that case the second display will only connect as HBR (since Thunderbolt 3 only has bandwidth for dual HBR2 or HBR3+HBR), so you better hope that they both connect with HBR2. In that case, you only need a DisplayPort 1.2 cable. But I would only buy the better quality DisplayPort 1.4 cables anyway.

If there is a problem with a display connecting as HBR3 not allowing a second display, I think there's a DisplayPort 1.2 mode you can set, then connect the second display, then set the first display back to DisplayPort 1.4 mode?

Question: can an Alpine Ridge support HDCP 2.2 at HBR2 or is a Titan Ridge required? Probably Titan Ridge is required to get all the DisplayPort 1.4 features.
 

d7d19285f0bd48

macrumors member
Original poster
Sep 13, 2020
36
37
Yes, 5120x1440 is fewer pixels than 4K so of course it should work with DisplayPort 1.2. I'm not sure what the Dell gets from supporting DisplayPort 1.4. HDR? DSC? YCbCr 4:2:0? This display needs none of those. The display supports HDCP 2.2 which comes from DisplayPort 1.3 - that's probably why DisplayPort 1.4 is supported.

If the display connects with HBR3, then a DisplayPort 1.4 cable will be required. However in that case the second display will only connect as HBR (since Thunderbolt 3 only has bandwidth for dual HBR2 or HBR3+HBR), so you better hope that they both connect with HBR2. In that case, you only need a DisplayPort 1.2 cable. But I would only buy the better quality DisplayPort 1.4 cables anyway.

If there is a problem with a display connecting as HBR3 not allowing a second display, I think there's a DisplayPort 1.2 mode you can set, then connect the second display, then set the first display back to DisplayPort 1.4 mode?

Question: can an Alpine Ridge support HDCP 2.2 at HBR2 or is a Titan Ridge required? Probably Titan Ridge is required to get all the DisplayPort 1.4 features.


Thanks.

And according to this KB article it appears to connect at HBR2.

Like I said, just going to pull the trigger and see what happens. 🤷🏼‍♂️
Might try several docks with an assortment of ports and just return what doesn't work.
 

joevt

macrumors 68040
Jun 21, 2012
3,324
1,527
Thanks.

And according to this KB article it appears to connect at HBR2.

Like I said, just going to pull the trigger and see what happens. 🤷🏼‍♂️
Might try several docks with an assortment of ports and just return what doesn't work.
Better make sure it's not using Tile Display mode. It can't use tiles if it only has one DisplayPort input and has no Thunderbolt input. Maybe they're saying "supporting Tile Display" as a description of DisplayID version 1.3 - not that they are using the Tile Display feature of DisplayID version 1.3.
 
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