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#1 2019-11-13 09:17:05

EchoJoe
Member
Registered: 2016-09-27
Posts: 10

Trouble setting up a external 144Hz monitor

Hello,

I need some advise setting up a 144Hz refresh rate display. Sorry if it has been asked before but I haven't been able to find anything with my hardware.

I have a:

  • Dell XPS 13 (9350)

  • Dell TB16 dock (which is being recognize OK and it supposedly has the capabilities of 144Hz) (I haven't been able to install the Thunderbolt 3 Firmware Update 4.26.11.001, A08 because requires windows environment.

  • Display cable

  • 144Hz monitor

When I visit Settings/Display on Gnome I can see the monitor being recognized and showing 3 different refresh rates:

  • 59.95 Hz

  • 119.99 Hz

  • 143.99 Hz

Which also aligns with the xrandr output

Screen 0: minimum 320 x 200, current 3840 x 2160, maximum 8192 x 8192
eDP-1 connected (normal left inverted right x axis y axis)
   3200x1800     59.98 +  59.96    59.94    47.99  
   2880x1620     59.96    59.97  
   ...
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-1-1 disconnected (normal left inverted right x axis y axis)
DP-1-2 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440     59.95*+ 143.99   119.99  
   1920x1080    120.00    60.00    60.00    50.00    50.00    59.94  
   1680x1050     59.95  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1440x900      59.89  
   1280x720      60.00    60.00    50.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32    56.25  
   720x576       50.00    50.00  
   720x480       60.00    60.00    59.94    59.94  
   640x480       75.00    60.00    59.94    59.94  
   720x400       70.08  
DP-1-3 disconnected (normal left inverted right x axis y axis)

where DP-1 is the XP13 monitor and DP1-2 is the external 144Hz monitor.

The issue arises when I try to select refresh rates other than 59.99 Hz on 2560x1440; monitor goes blank (no image) and gnome holds it until it reverts back to 59.99Hz and I get the image back. However, I can use other resolution - for example - 1920x1080 @ 120.00 Hz, or any other supported, without a problem.

Other test I  have done, is to use mirror screen @ 144Hz; it sort of works but it glitches out (random lines on the image).


Do you think this might be the internal XPS13's graphic's card not being able to handle it?
Is there anything else I can try?
This post was solved by using cvt12 Should I give it a go?
Could you advise me where else to look at?

Thank you in advancde.

Last edited by EchoJoe (2019-11-13 09:22:10)

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#2 2019-11-13 12:48:45

seth
Member
Registered: 2012-09-03
Posts: 19,810

Re: Trouble setting up a external 144Hz monitor

This post was solved by using cvt12 Should I give it a go?

Sure, why not. It will significantly lower the pixelclock demand - still more than regular 3200x1800@60 but worth a shot. (idk at hand how to query the HW limits on intel chips, but you could google the spec for your actual IGP)

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#3 2021-02-09 05:56:50

EchoJoe
Member
Registered: 2016-09-27
Posts: 10

Re: Trouble setting up a external 144Hz monitor

Hello @seth

After a whole troubling 2020, I have been able to try again to make the monitor to work at 144hz. I hope you could give me a hand again.

I have updated my XPS 13 (9350) with the latest thunderbolt 3.2 firmware without issues following this
command fwupdmgr get-devices tells me that there might be a new BIOS update 1.13.0 but I havent checked since must very recent,

Coming back to subject, I have been able to get some video output @ 143.99hz using Gnome. I set the refresh rate to 143.99Hz, once the screen goes blank (no output) I press enter to Keep settings so my screen stays blank. Then I disconnect USB3.1 thunderbolt 3.1 and reconnect and I then get some video but very glitchy... vertical lines and sudden blank screen quite often (every 10s).

It is not very usable but I can play with ctv this way to see if I get better results:

this is how I normally run the screen with no problem

xrandr --verbose --output DP-1-2 --mode 2560x1440 --rate 59.95 --scale 1.5x1.5

also 1920x1080 @ 120.00hz works as well.

This is the output of cvt

$ cvt 2560 1440 143.99
# 2560x1440 143.87 Hz (CVT) hsync: 225.59 kHz; pclk: 808.50 MHz
Modeline "2560x1440_143.99"  808.50  2560 2792 3072 3584  1440 1443 1448 1568 -hsync +vsync

When I use cvt12 to reduce pixelclock I get this

$ cvt12 2560 1440 143.99 -b
# 2560x1440 @ 143.990 Hz Reduced Blank (CVT) field rate 143.990 Hz; hsync: 222.177 kHz; pclk: 586.55 MHz
Modeline "2560x1440_143.99_rb2"  586.55  2560 2568 2600 2640  1440 1529 1537 1543 +hsync -vsync

neither cvt nor cvt12 commands have helped. Both give me glitchy video output... not improvements... How do I know what is the right pclk on HW limits on intel chips at such refresh rate?

cheers.

Last edited by EchoJoe (2021-02-09 05:57:39)

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#4 2021-02-09 15:46:17

seth
Member
Registered: 2012-09-03
Posts: 19,810

Re: Trouble setting up a external 144Hz monitor

Does it work at 120Hz (w/ reduced blanking)?
I suspect something™ in the chain only provides 2 Dp1.2 lanes (and I suspect it to be the dock, so if you've the chance to use a direct adapter/cable that utilises all lanes for the display port…)
There also seems to be a dual display adapter (TB 3Type C) that cobines two outputs and will likely be required for the desired output w/ this dock. Do you have that?

The IGP will likely be more bothered by the scaling, so if things work fine one a mirrored output but not in a horizontal layout, the limitation will be in that area. You could try a vertical output.
Another thing to try (voodoo science) would be to disable MST in the Monitor.

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#5 2021-02-23 01:23:08

EchoJoe
Member
Registered: 2016-09-27
Posts: 10

Re: Trouble setting up a external 144Hz monitor

Thank you Seth for your ideas.

I tried a better quality cable and 2560x1440@120 works!! Sometimes I forget to try the more obvious ideas. Do you think making 120Hz to work, dock has hope for 144?

xrandr --verbose --output DP-1-2 --mode 2560x1440 --rate 119.99 --scale 1.5x1.

Unfortunately, 2560x1440@143.99 still glitchy but much much more stable than before. Image still jumps with some weird lines on the right hand side of the screen; Blank screen not as often. Cable is a 2m; would a 1.5m perform better?

I tried to boot OS without scaling to then apply 143.99 using Gnome and xrandr but same glitchy behavior.

My setup currently use Single Display (Not joined, not mirrored, but regardless, in both of those settings, behavior is the same, 2560x1440@120 works, 2560x1440@144 glitchy.

Seems like monitor does not have MST. I'll definitely try Type C to display adapter to rule out the dock.

cvt12 on reduced blank still has no effect on 143.99 sad.

cheers.

Last edited by EchoJoe (2021-02-23 01:28:40)

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#6 2021-02-23 08:05:14

seth
Member
Registered: 2012-09-03
Posts: 19,810

Re: Trouble setting up a external 144Hz monitor

"#1: it's always the cable" --- me, all the time ;-)

Cable is a 2m; would a 1.5m perform better?

If everything else was the same, yes.
But you can easily have a 3m cable outperform a 50cm cable if the latter is just poor quality.

Did the 120Hz work w/o reduced blanking (which is at 661.25 MHz while reduced blanking at 140Hz would get the clock down to 586.59 MHz so it should not be the limiting factor)

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