Windows 10: How to keep HDR display mode while the desktop PC is on external battery power?

How do you prevent Windows 10 desktop PC from turning off the HDR display mode when the computer switches to battery power during a power grid outage?

:)

 

External display turned black after turning on HDR (and I can't turn it off)

I connected my work laptop to an external display at home via a usb c dock. I was using the built in display and external display in extended mode. I looked through the display settings in windows 10 and thought I'd try HDR on the external display since it is HDR capable. I toggled HDR on and the external display turned black. After a short time the external says it's not receiving signal and turns off. When I look at display settings for the external display in windows, there is no option to turn off HDR.

If I switch to mirrored display mode both displays work. If I disconnect power from the laptop the external display works even in extended mode. My understanding is that these options turn HDR off. But how do I turn HDR off when the laptop is connected to power and the displays are in extended mode? I can also say that the external display works in extended mode when I connect it directly via HDMI, since HDR is not turned on with that output.

I searhed and found some people have asked the same question but the answers containted no working solution.

 

Adjust brightness of external display in HDR

Hello everyone,

I own an Asus Zephyrus M16 2023 which has a MiniLED display. The brightness is really great but I wanted to get a second, slightly larger external display to support daily content consumption. The one I bought is actually an modified display from the Asus ROG Strix G18 2024 (just the display built into a case with DP, USB-C ports and brightness control) which has a 18 inch MiniLED display with double the dimming zones. Problem is, when connecting the external monitor and switching on HDR, the modified G18 display reverts to about 80% brightness. Usually you can increase it on the main display with the built in brightness control buttons. The buttons on the external one are not working.

When not in HDR, the brightness control of the external one is usuable and the display reaches the same brightness as the main display in HDR but does not activate/deactivate the dimming zones. This results in either having HDR off and getting the peak brightness but no good blacks or having HDR enabled and getting the local dimming but not getting the brightness peaks as the main display.

I'm not sure if that is because of the abnormal nature of the external display (modified laptop display) or if it is a software restriction. I also tried the app Twinkle Tray from the Windows Store. Although it is recognized, modification of brightness through the app is not supported.

Edit: it seems to be an issue with the power delivery of the external display. When powering it through the accompanying power supply adapter from a power outlet the peak brightness is reached. Regardless of which cable (power or video) I connect with which laptop port, the external display can't reach its full brightness. Thats strange because on paper the PD over DP should supply 100W which I deem to be enough.

**** moved from german to english Community ****

 

HDR on duplicate displays in Windows 10

Dear Greg,

Thanks for your answer. Sorry for my late reply. I posted the question and then was away for a few days and forgot to check for answers.

Setting the resolution of the monitors separately doesn't seem to fix the issue. The HDR option is still not available.

I did some more searching and found this article from Microsoft suggesting that it may not be possible to have HDR on two duplicated displays at the same time.

HDR settings in Windows - Microsoft Support

"When you first connect an external display to a laptop, Windows will duplicate your desktop on both displays by default. However, HDR isn’t supported in this configuration. To view HDR content on the external HDR monitor
or TV, extend your desktop across both displays."

I'm connecting two displays to a desktop PC, but I imagine the same rules apply there as well. It's strange that Windows doesn't support this. There doesn't seem to be any technical reason why it wouldn't work.