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Multiple monitor issue using Intel UHD 620

KNORSTU
Beginner
314 Views

Hi. My laptop has an Intel UHD 620 graphics card. The card has the latest driver. I'm using a USB-C docking station with 3 monitor connections, 2 display ports, 1 HDMI. I'm using 3 identical Dell monitors. They support 1920X1080 max resolution. When connected, 2 monitors are 1920X1080, 1 monitor is 640X480. When I look in the Graphics Command Center, it shows that monitor as 640X480 and I am unable to select the finer resolution. If I try a custom size, it tells me 1920X1080 is already a mode which exists. If I unplug a monitor with the high resolution, my problem monitor resets to 1920X1080.

Any ideas? Thanks.

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3 Replies
AlHill
Super User
301 Views

UHD 630 three monitor support includes the laptop screen. 

https://www.intel.com/content/www/us/en/support/articles/000025673/graphics.html

Doc (not an Intel employee or contractor)

KNORSTU
Beginner
296 Views

Given the link to the doc you sent, I'm using table 1. My laptop is closed so not using the built-in display.

n_scott_pearson
Super User Retired Employee
289 Views

You are getting exactly what I would expect. Let me explain...

  1. The UHD 620 graphics engine is capable of outputting in DisplayPort 1.2 format. This means that it is capable of supporting a maximum data rate of 17.28 Gb/s. Applied across the four channels of the USB-C connection, that's a maximum data rate of 4.32 Gb/s over each channel.
  2. When you connect a dock over USB-C that also supports USB, only two channels of four are available for graphics transmission. That's a maximum data rate of 8.64 Gb/s.
  3. In order to support a 1080p@60Hz monitor, a data rate of 3.2 Gb/s is needed. Two monitors means 6.4 Gb/s. Essentially, then, a data rate of only 2.24 Gb/s is available to support a third monitor. This is not enough to support a 1080p@60Hz monitor.

So, what are the choices for the third monitor? A smaller resolution at 60Hz or the same resolution at 30Hz. Which way(s) it can go is dependent upon the monitor. If it is insisting on 60Hz, then down goes the resolution. The question is: will it go down to 30Hz and let you keep 1080p? That is for you to determine; try 1080p@30Hz.

Hope this helps,

...S

P.S. Transmission rate information comes from here: https://en.wikipedia.org/wiki/DisplayPort.

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