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2020 MacBook Pro 8th Gen with 2 4K displays

citivolus said:
Well thankfully they arrived a day early! I set up the displays and they are absolutely stunning. I am running them at a Scaled resolution with a "looks like 2560 x 1440".

Very happy with the displays!

First I tried the 8th Gen and sure enough, I was only able to get the two displays to run at 30Hz. The desktop was very choppy just when moving windows. I pretty much stopped right there as there was no point in going on. Pretty bummed.

Next I tried the 10th Gen and they were able to display the same resolution at 60Hz. Moving windows around was very fluid. I played some 4K videos and they were very smooth. This is due to the fact that the Ice Lake chipset supports HBR3 (as I've read it has to do with greater bandwidth via USB-C). The 8th Gen only supports HBR2 so it could only connect at 30Hz.

Overall I would say as has been suggested on this forum, the 8th Gen cannot handle two 4K displays @60Hz while the 10th Gen does so very well. Just sucks that Apple forces me to upgrade to the 10th Gen with a $500 premium to do so. I get that there are other benefits, but the graphics capability is pretty fundamental to me.
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FYI, I'm 99% sure that you not being able to achieve 60hz on the 8th gen is either a bug or some kind of cable/adaptor compatibility issue.

While I may not be happy with the performance of my MBP 2018 13", you certainly CAN get two 4k/60Hz displays (with looks like 1080P or 1440P) working with machines based on the 8th gen.

That said, it IS sometimes rather finicky, requiring some fiddling in the display menu, to get both displays running at 4K/60Hz.

Nonetheless I'll reiterate that while it does work, performance is not consistent enough that I can recommend it if you depend on a dual monitor setup on a daily basis.
 
WickedPorter said:
I used a 2018 MBP 13" for quite a while connected to two Dell P2415Q monitors at work. I used USB-C to DisplayPort cables (Accell brand supporting DP Alt Mode) and it always worked very well for me. Both cables connected to the two TB3 ports on the right side of the machine. Worked in all scaling modes ... for the 4K monitors, I used the option one from the left, can't remember what "looks like" resolution that was. All other scaled resolutions worked well too. Did not use "clamshell" mode ... the 13" display was my third monitor.

ETA: Both ran at 60Hz with no issues. It was the i5-8259U with Iris Plus 655 GPU.
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That is great to know as I'll be running a 4k at home setup with the 8th gen i think.
Did you have any strange 'choppiness' at all? I was looking at USB-C monitors which is effectively DP with a different connector
 
unoporfavor said:
That is great to know as I'll be running a 4k at home setup with the 8th gen i think.
Did you have any strange 'choppiness' at all? I was looking at USB-C monitors which is effectively DP with a different connector
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Zero chop, worked perfectly. Never had any issues with two 4Ks daily, smooth as butter. Just make sure your cable supports DisplayPort Alt Mode, as this is the most “native” way to connect monitors in this case. Stay away from anything requiring drivers, i.e. “DisplayLink” which is basically displays over USB.
 
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WickedPorter said:
Zero chop, worked perfectly. Never had any issues with two 4Ks daily, smooth as butter. Just make sure your cable supports DisplayPort Alt Mode, as this is the most “native” way to connect monitors in this case. Stay away from anything requiring drivers, i.e. “DisplayLink” which is basically displays over USB.
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Do you think this is why others are having issues etc?
 
Mattyman said:
Do you think this is why others are having issues etc?
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Very likely. I’ve used this same config with multiple 13” and 15” MBPs (2016-2020) and never had an issue. With proper DP Alt Mode cables (USB-C to DisplayPort), all of the MBPs always worked smoothly with two 4Ks @ 60Hz.
 
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citivolus said:
Well thankfully they arrived a day early! I set up the displays and they are absolutely stunning. I am running them at a Scaled resolution with a "looks like 2560 x 1440".

Very happy with the displays!

First I tried the 8th Gen and sure enough, I was only able to get the two displays to run at 30Hz. The desktop was very choppy just when moving windows. I pretty much stopped right there as there was no point in going on. Pretty bummed.

Next I tried the 10th Gen and they were able to display the same resolution at 60Hz. Moving windows around was very fluid. I played some 4K videos and they were very smooth. This is due to the fact that the Ice Lake chipset supports HBR3 (as I've read it has to do with greater bandwidth via USB-C). The 8th Gen only supports HBR2 so it could only connect at 30Hz.

Overall I would say as has been suggested on this forum, the 8th Gen cannot handle two 4K displays @60Hz while the 10th Gen does so very well. Just sucks that Apple forces me to upgrade to the 10th Gen with a $500 premium to do so. I get that there are other benefits, but the graphics capability is pretty fundamental to me.
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What cables did you use? DisplayPort compatible?
 
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WickedPorter said:
Very likely. I’ve used this same config with multiple 13” and 15” MBPs (2016-2020) and never had an issue. With proper DP Alt Mode cables (USB-C to DisplayPort), all of the MBPs always worked smoothly with two 4Ks @ 60Hz.
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Thanks so much for your knowledge on this. Is it possible to use usb-c to usb-c connection cable and have this DP alt mode?
Hope that makes sense.
I want the charging capabilities of usb -c that I guess your usb-c to DP can't do?
Cheers!!
 
Mattyman said:
This issue sounds like a compatibility issue on the cable side or even monitor setup? 30hz is always going to be choppy
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Maybe I am not very observant but my 2015 12” MacBook driving my 4K display really looks pretty good. Videos don’t even look too bad, especially considering that I only get it to work at 30Hz.
 
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so - problem solved - its in the detail. The manual for displays in question quote for USB-C connectivity:

. If source is HBR3, the maximum resolution is 3840 x 2160@60 Hz and USB 3.0 data. If source is HBR2, the maximum resolution is 3840 x 2160@30 Hz and USB 3.0 data. #

Therefore if you want 60Hz - go for display port cables! We all know that 8th gen cannot support HBR3
 
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Mattyman said:
so - problem solved - its in the detail. The manual for displays in question quote for USB-C connectivity:

. If source is HBR3, the maximum resolution is 3840 x 2160@60 Hz and USB 3.0 data. If source is HBR2, the maximum resolution is 3840 x 2160@30 Hz and USB 3.0 data. #

Therefore if you want 60Hz - go for display port cables! We all know that 8th gen cannot support HBR3
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Legend! Well done.
Does that mean you can use usb-c cables with alt DP mode to get power and still have 4k 60hz?
 
Mattyman said:
so - problem solved - its in the detail. The manual for displays in question quote for USB-C connectivity:

. If source is HBR3, the maximum resolution is 3840 x 2160@60 Hz and USB 3.0 data. If source is HBR2, the maximum resolution is 3840 x 2160@30 Hz and USB 3.0 data. #

Therefore if you want 60Hz - go for display port cables! We all know that 8th gen cannot support HBR3
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Thanks Mattyman, I was going to post similar info. The 8th Gen only supports HBR2. It CAN support 60Hz at 1080p which comes up in System Preferences as "Default for Display". Any scaled resolution results in 30Hz. Also, if your monitor has a USB hub (like the Dell U2720Q I am running), it will only run those USB ports at 2.0 speeds. This is particularly notable if you plan to use a device like a gigabit ethernet dongle in addition to the two displays, given the 8th Gen only has two ports.

The 10th Gen supports HBR3. This means that it CAN support scaled resolutions (like 2560 x 1440 which I am running) at 60Hz AND run the monitor's USB hub at 3.0 speeds.

Regarding cables, I am using the USB cables that came with the monitor. My testing of both laptops used the same cables. Given I was able to achieve desired results with the 10th Gen, I would presume that the cables that came with the monitor are appropriate. The only issue is that they are annoyingly short.

Hope this answers the questions.
 
citivolus said:
Thanks Mattyman, I was going to post similar info. The 8th Gen only supports HBR2. It CAN support 60Hz at 1080p which comes up in System Preferences as "Default for Display". Any scaled resolution results in 30Hz. Also, if your monitor has a USB hub (like the Dell U2720Q I am running), it will only run those USB ports at 2.0 speeds. This is particularly notable if you plan to use two displays and a device like a gigabit ethernet dongle, given the 8th Gen only has two ports.

The 10th Gen supports HBR3. This means that it CAN support scaled resolutions (like 2560 x 1440 which I am running) at 60Hz AND run the monitor's USB hub at 3.0 speeds.

Regarding cables, I am using the USB cables that came with the monitor. My testing of both laptops used the same cables. Given I was able to achieve desired results with the 10th Gen, I would presume that the cables that came with the monitor are appropriate.

Hope this answers the questions.
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So I think we are saying if you get the correct cable the 8th gen should work ok?
 
Mattyman said:
Therefore if you want 60Hz - go for display port cables! We all know that 8th gen cannot support HBR3
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My 2018 MBP 13" with 8th gen i5-8259U supported HBR3 ... does the 2020 13" 8th gen not? Is there info somewhere on this?

ETA: Nevermind, I'm wrong. https://www.macrumors.com/2018/07/20/2018-macbook-pro-titan-ridge-displayport/

Odd... I was able to use two 4K displays with the DP Alt mode cables with this, both running at 60Hz. I wonder if it had something to do with 4 vs 2 TB3 ports?
 
WickedPorter said:
My 2018 MBP 13" with 8th gen i5-8259U supported HBR3 ... does the 2020 13" 8th gen not? Is there info somewhere on this?

ETA: Nevermind, I'm wrong. https://www.macrumors.com/2018/07/20/2018-macbook-pro-titan-ridge-displayport/

Odd... I was able to use two 4K displays with the DP Alt mode cables with this, both running at 60Hz. I wonder if it had something to do with 4 vs 2 TB3 ports?
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This is only relevant on the cable itself. If you used usb to display port that would work. If you used usb c to usb c it would be limited to 30hz
 
Mattyman said:
So I think we are saying if you get the correct cable the 8th gen should work ok?
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Sorry no, I am saying that it depends on what your priorities are. The cable that comes with the monitor is appropriate, it is just short. I don't believe that you can get a scaled resolution greater than 1080p with HiDPI enabled at 60Hz with any cable.
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Mattyman said:
This is only relevant on the cable itself. If you used usb to display port that would work.
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Do you have a source for this?
 
citivolus said:
Sorry no, I am saying that it depends on what your priorities are. The cable that comes with the monitor is appropriate, it is just short. I don't believe that you can get a scaled resolution greater than 1080p with HiDPI enabled at 60Hz with any cable.
[automerge]1590673255[/automerge]

Do you have a source for this?
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Yes - WickedPorter confirmed he gets 60Hz - but he used USB C to display port. The Dell manual explicitly says if the computer is HBR2 compatible - then it is limited to 30hz for USB C to USB C. It is silent on the display port cable, as that will work at 60hz.
 
citivolus said:
This thread has good info about this topic: https://www.dell.com/community/Monitors/U2720Q-MacBook-Pro-29Hz/td-p/7532811

Regarding using a USB-C to DisplayPort cable, I'm not sure how that would help because wouldn't the USB ports on the monitor be unusable then? This is important given the 8th Gen only has two USB ports.
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I don’t have this set up. Just saying the display port cables appear to work better. Obviously some compatibility issues with usb c to USB-C with older type macs.
 
citivolus said:
This thread has good info about this topic: https://www.dell.com/community/Monitors/U2720Q-MacBook-Pro-29Hz/td-p/7532811

Regarding using a USB-C to DisplayPort cable, I'm not sure how that would help because wouldn't the USB ports on the monitor be unusable then? This is important given the 8th Gen only has two USB ports.
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Yes, the Accell USB-C to DP cables I used only worked for monitor signal, nothing else. Just to clarify, when I reference the USB-C to DisplayPort Accell cable, I'm not actually using anything "USB data" related with this cable. I'm using the "DisplayPort Alt Mode" functionality of the MacBook Pro USB-C/Thunderbolt ports.

Worth mentioning and might be an option with limited port availability: I also had no issues using a CalDigit TS3+ Dock running two 4Ks @60Hz ... the TS3+ has a full size DisplayPort port (used for 4K monitor 1) as well as a TB3 port (used for 4K monitor 2 using the previously mentioned Accell USB-C to DP cable). This off one dedicated TB3 cable connecting the dock to the MacBook Pro.
 
WickedPorter said:
Yes, the Accell USB-C to DP cables I used only worked for monitor signal, nothing else. Just to clarify, when I reference the USB-C to DisplayPort Accell cable, I'm not actually using anything "USB data" related with this cable. I'm using the "DisplayPort Alt Mode" functionality of the MacBook Pro USB-C/Thunderbolt ports.

Worth mentioning and might be an option with limited port availability: I also had no issues using a CalDigit TS3+ Dock running two 4Ks @60Hz ... the TS3+ has a full size DisplayPort port (used for 4K monitor 1) as well as a TB3 port (used for 4K monitor 2 using the previously mentioned Accell USB-C to DP cable). This off one dedicated TB3 cable connecting the dock to the MacBook Pro.
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Why do you need data to go to a monitor? I understand you can get power feed but not sure my you need data going there. I assume display port does provide power to the Mac?
 
Mattyman said:
Why do you need data to go to a monitor? I understand you can get power feed but not sure my you need data going there. I assume display port does provide power to the Mac?
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To use the USB hub built-into the monitor. Also I think you're right that you can't get power to charge your MacBook if you are using a USB-C to DisplayPort cable.
 
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