Multi-monitor set-up - occasionally things shift to the inactive screen + other screen issues

[KFrohman]

Three monitors with three different resolutions (one is 4K via HDMI, one is 1440p via DVI and one is 1080p via HDMI to DP connector), all connected to the same GPU (GTX 1070). The 4K screen is the 'inactive' one, being a television it's not often I require it to be on and wasting power when all it's used for is desktop space outside of watching movies or whatever. I'd expect Windows 10 to have a handle on this, but it doesn't. Despite having the primary monitor as the 1440p screen, there'll be occasions where booting or coming back from locking the PC, the two screens on my desk will just show black until I turn the TV on, then I get picture on the main screens. Even minimising an application can cause it to spring back on the 4K screen even though it's turned off. More recently however, when I lock the PC I expect the screens to actually turn off after 10 minutes as set in my power plan, but instead windows just outputs black, never actually shutting down the video output, so the monitors can't standby on their own accord.
I thought I could live with the small niggles but it's getting worse as the weeks go on. Please, someone tell me there's a simple and easy solution to this, it shouldn't be this complicated.

[KFrohman]

Not it, none of my monitors nor the TV have such a function.

[Snek]

Windows 10 can sometimes be an ass about setting the wrong monitor as the primary monitor when it detects a different monitor configuration than usual, as is the case when your 4KTV is off but set as the main monitor.

When the 4K monitor is off, if you press Win+P 1-3 times and wait a few seconds, it may switch the projection mode (extend, duplicate, etc) so that you can duplicate the 4K to something else, and then you might be able to set the main monitor whatever specific monitor configuration Windows is detecting then.

Display driver oddities can cause this same issue as well so running Display Driver Uninstaller and grabbing the latest can help sometimes, if even just to reset all monitor configurations to the default (which usually happens to be Duplicate).

Source: KVM switches are assholes

[Neckername]

You are also trying your luck by using adapters. Some designs don't allow certain "metadata" to pass through such as monitor info and refresh rate limits and what not. If you can try using all of the same connectors (ex: use 3 display port cables if possible or, 2 DP's with one DP to HDMI for the TV). Then try setting these things in your driver settings. NVidia and AMD both offer a lot more options for monitor configurations in the driver settings. Below is a picture of the options to detect monitors in NVidia control panel. Using different detection methods may help when using TVs, cable adapters, etc.

[IMG]https://i.gyazo.com/8ac10bfdd59fa5f751cad13b569708f1.png[/IMG]