A while back I stopped paying for consoles and put my efforts to a good PC rig. However I still like laying down on the couch and using a XBOX Controller. Moonlight fixed this for me (using a 4K Apple TV and full ethernet) . Full FPS, full resolution (with RTX I might add), no lag, perfection!
But there was a problem when I upgraded my PC. Moonlight kept using the right (wrong) monitor instead of dead center. This made it so I would have to get up, go in my office and force the game onto the wrong monitor (or worse).
However after a lot of trial and error I figured out how to fix it.
First you need to make sure the monitor in question is in fact the “BIOS Default”. What does that mean? Well for me, when I power on the tower the Dell logo shows up on that screen. I had to swap around DP cables until that happened.
Next you need your preferred monitor to be the Windows first found. Notice I didn’t say primary? NVidia doesn’t respect the primary monitor flag (they should but they dont).
Some background: Windows makes “profiles” for every unique pairing of monitors. It does this by using Monitor Serial Numbers which is why swapping cables doesn’t really fix the issue. My assumption is NVidia looks for Monitor 00 and that’s the one it uses. So the real trick is to get WINDOWS to address your preferred monitor first.
To get Windows to make your preferred monitor #00 (what I am calling first found) you need to figure out which cable its connected to. Make sure its the only one attached, then go to the following section of the registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Configuration
Delete all the sub keys of Configuration. I did this a few times, never did me much harm although be aware it could create issues for you. A system restore point might be a good idea or at least an export of Configuration *(right click -> export).
Then disconnect all other monitors except the one you care about and reboot. Once rebooted plug in your other monitors. You will have to reorder them again. And that should do it.
I figured this out after realizing even after purging drivers and configs I found it odd Windows always knew how to put the monitor order back to gather again (even when swapping cables). That is how I found these keys which kills that saved profile. The only other part to figure out was how to make sure the monitor I cared about was first.
Hope it helps and happy gaming!