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I have a Windows 10 notebook (Thinkpad T460p) that I pretty much use as a stationary PC. When I'm working I connect it to an external monitor. I also connect it to my TV a lot to watch movies or streams on there.

I used to always switch cables manually between the monitor and TV, and apart from being a bit of a hassle everything worked fine. Today I finally got myself a HDMI hardware switch (https://www.amazon.com/dp/B079JQ9XXV) for making the switching process a bit more comfortable.

Everything works so far, except the resolution doesn't change automatically when switching. My monitor is 1920x1200, and my TV is 1920x1080. When I press the switch button, the resolution stays the same as it was before. When I then unplug the screen and plug it back in, it switches to the correct resolution.

It seems to me that the switch is making the switching too fast for the graphic card to notice, which makes the card think it is still connected to the same monitor, and therefore it is not refreshing the resolution settings.

Is there any (preferably software-based) trick I can use to get the graphic card to recognize the monitor switch and change resolution automatically?

Edit: Failed to mention I'm using a docking station. Which would've been quite essential.

MaxD
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  • Have you considered a 3 output switch, leaving output 2 disconnected? Connect the monitor to output 1 and the TV to output 3, when you switch between them just pause on the unused output 2 momentarily. Just a thought. – acejavelin May 26 '20 at 21:54
  • @acejavelin Not at all, but I'm definitely gonna look into that. – MaxD May 26 '20 at 22:00

2 Answers2

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Your switch apparently does not support EDID in a smart way, or the TV does not furnish any, as otherwise the resolution change would have been automatic.

The solution would be using some product that allows easy switching between resolutions. This will require an extra step (usually a click) when switching between the displays.

An example of such a product is the free Monitor Profile Switcher, but others can be found.

Another example is WS Display Settings (7,20 €), where the free version posts a dialog every time it is run. See this answer for more information on how to run it.

Once the docking station entered the picture, the problem became much clearer.

The dock in this case seems to helpfully cache the EDID data of the connected monitor, and doesn't notice that this monitor was switched.

Windows regularly interrogates the port for the EDID data of all connected monitors, in order to detect any changes. This didn't work for you, since the dock kept on returning the cached EDID data, with the resolution of the first monitor that it found connected.

Disconnect and reconnect of the display cable fixes the problem. The dock again "discovers" the monitor, requests its EDID data and communicates it to Windows, which on its side changes the resolution accordingly.

A better method than connect/reconnect of the cable would be getting a better dock (which may be impossible in this case).

harrymc
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  • Seems it had something to do with the docking station I'm using, see my answer. I'm completely baffled, would've never expected this. Thanks for being so persistent at trying to help me, really appreciate it. – MaxD May 27 '20 at 14:17
  • Explanation: The docking station seems to helpfully cache the EDID data of the connected monitor, and doesn't notice that the monitor was switched. Disconnect/reconnect fixes the problem by the dock again "discovering" the monitor, then the new EDID is communicated to Windows which changes the resolution accordingly. Mentioning the dock in the post would have saved us a lot of time. For a better method I would suggest getting a better dock. – harrymc May 27 '20 at 14:26
  • As the docking station has some other display ports, I initially wanted to avoid suggestions that include using one of them instead of the switch, as I really like having a dedicated mechanical button. When things turned more and more complicated I should've absolutely mentioned it, and in retrospect I feel pretty dumb for not doing so, but this being the reason never occurred to me in the slightest. It's an original Lenovo dock which connects to the notebook through a special socket at the bottom, so probably there isn't any better one I could get. – MaxD May 27 '20 at 14:35
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It's unbelievably stupid, but I finally found out that the reason seems to be the docking station I'm using for my notebook.

When I connect the cable to the HDMI port of the docking station, it gives the problems described above. When I use the HDMI port of the notebook itself, the active signal resolution changes automatically without any issue.

This still is not a 100% satisfying solution as I will have to unplug the cable every time I'm taking the notebook with me, but I do that less than switching between monitor and TV so overall it's an improvement.

MaxD
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