I am using RealVNC at work to connect to a remote PC. When not working on that PC directly, I prefer to keep the monitor off. However when the monitor is off, RealVNC Server reduces to reduce the desktop resolution from 1920×1080 of the monitor to the maximum of 1600×1200. It happens in real time: When connected, I can see the resolution numbers changing in Display > Screen Resolution while switching the remote PC monitor on and off. I wonder if it is possible to control it. I want to keep the high resolution even with the remote monitor switched off.
I've tried reading through the options of both VNC Server and Viewer, but cannot find anything related. The -geometry option mentioned in another thread does not exist in my configuration. I am running Windows 7 on both local and remote systems, with RealVNC version 5.0.3.
Best Answer
If your monitor is hooked up via DisplayPort or HDMI then when you turn it off the computer sees it as "disconnected", as if you pulled the cord out from between them.
For more info on that, check out this other SU question: Turning DisplayPort monitor off disables monitor completely
Since the display is disconnected, Windows and/or your display driver will revert to its favorite desktop resolution. Yours seems to be picking the highest non-wide/4:3 ratio it supports (UXGA).
Since VNC uses a capture of the actual desktop, it will/can only show you the resolution that the desktop is set to.
From my experience VGA and DVI connections don't register as "disconnected" when turned off, so if your monitor and video adapter have one of these alternate connection types, I'd suggest trying those to see if your chosen resolution "Sticks" when the monitor is off.