Intel(R) UHD Graphics 620 display-hdmı multiport Refresh frequency problem

[kaganmersin]

Hello 

I have laptop that using Intel(R) UHD Graphics 620. When I plug in monitors with HDMI and Display ports together to my laptop through the docking station I see that my primer laptop which plugged in through the Display port providing 60 Hz even though I have a 144 Hz monitor. But when I disconnect the seconder monitor that plugged on through HDMI and leave just primer monitor as plugged in I see that my primer monitor providing 144 Hz as expected. I do believe that it is not related hardware level because as you can see in screenshots I can see 144Hz as expected. (in case of disconnet seconde monitor )

You can find Intel Graphic Control Center screenshots.
P.S. : My drivers has been updated as Lenove offer in official website (https://pcsupport.lenovo.com/tr/en/products/laptops-and-netbooks/thinkpad-x-series-laptops/thinkpad-x390-yoga/20nq/20nqs3fl1t/r90z8jd2/downloads/driver-list/component?name=Graphics%20Processing%20Units%20%28GPU%29) (version: 27.20.100.9168)

[n_scott_pearson]

Only a single DisplayPort (DP) channel is being provided to the dock, so if you connect two monitors to this dock, regardless of interface type (DP or HDMI), they are sharing the bandwidth of this single DP channel. This is going to prevent you from running 144Hz when two monitors are connected, unless they are 1080p monitors (and perhaps not then).

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[kaganmersin]

Hello,  first of all, thanks for information. The question is that what can I do to get 2 x 144 Hz from my dual monitor or at least take 144Hz from one of them? If I use USB C to 2 x 4k HDMI/or Displayport adapter and plug-in USB-C to a laptop directly, Will I able to get it? I just want to understand that sharing bandwidth related with just dock also exist or not for laptop If I plug-in adapter to the laptop directly via USB-C (USB C to 2 x 4k HDMI or Display port). Second thing comes in my mind what happen if I plug in one monitor to laptop with HDMI and another monitor is HDMI to USB-C, still, I can not get 2x 144 Hz? By the way I am open to any other solution to get 2x 144 Hz.  

[n_scott_pearson]

You will have a chance of getting it working with a USB-C-to-2xDP or USB-C-to-2xHDMI adapter but you will never get it to work with that dock.

I brainfarted when I generated my previous response (sorry). The reason why it will not work with the dock is because, if the dock is also utilizing the USB 3.x signal that is present in the cable from the PC, then the bandwidth of the DisplayPort signal available is cut in half. 

To explain that statement, understand that the USB-C cable has four 'pipes' for sending/receiving data. If you are using the USB-C cable exclusively to deliver the DisplayPort 1.2 signal, it can use all 4 pipes and deliver the full bandwidth of this signal (which is sufficient to handle a 4K@60Hz monitor connection). If a USB 3.x signal also needs to be passed, however, this will take over one or two of the pipes, cutting in half what is available to deliver the DisplayPort 1.2 signal (so now only sufficient to handle a 4K@30Hz monitor connection). If you are using 1080p monitors, one could be connected at 144Hz, but two could only be connected at 60Hz each or possibly one at 85Hz and one at 60Hz.

With a USB-C-to-2xDP or USB-C-to-2xHDMI adapter, no USB 3.x is required and all four pipes remain available. This means two 4K monitors at 30Hz or two 1080p monitors at 144Hz.

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[n_scott_pearson]

If your laptop has both USB-C and HDMI 2.0 connectors, you should easily be able to connect a monitor to each at 144Hz (provided good USB-C-to-HDMI or USB-C-to-DP adapter). If the HDMI port is a direct-connect to the processor (i.e. no LSPcon converting DP 1.2 to HDMI 2.0) - which means only HDMI 1.4a, then best you could do is 120Hz.

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[AndrewG_Intel]

Hello @kaganmersin

Thank you for posting on the Intel® communities.

We hope that the information provided by the community has been helpful. We understand you have opened a Web Ticket with us. We will therefore close this community case from our side but we will leave the thread open so interactions with community peers may continue.

If you need further assistance from Intel regarding this matter, we will continue to help you through the internal Web Ticket. Thank you for your understanding.

Best regards,

Andrew G.

Intel Customer Support Technician