I currently work with a three monitor set-up (side by side by side) on an Ubuntu 18.04 LTS Desktop.
I am presently upgrading some hardware that's not all computer related but want to get this sorted out so I can work on my cable management.
I have a small UPS for short power outages, but it would obviously last longer and be more efficient if it only needs to power a single monitor, rather than all three.
Is it possible for me to view what's on the other two displays on the primary monitor? Or would I have to keep all three on while I manually move active windows to the main monitor, and then turn the monitors off manually?
It's not a super powerful UPS and I only get 60 minutes of downtime with all three monitors, the computer, the router, the switch and the modem to keep me online; but I want to reduce that load by having the other two monitors turn themselves off and not be involved with the UPS at all.
I am aware manually moving things to the primary monitor doesn't take that much time and is very easy, but I'm not always at the computer when the power drops; so until I actually notice, or get to the computer, I could have lost 80% of my UPS charge. In the winter, short outages are quite common here so I'm not looking to upgrade the UPS to last for hours/days; 99% of the time, power is back on within the hour, so it's plenty powerful enough for me, and was cheap.
Try this: put some windows on all three displays, then disconnect the secondary displays and see if the windows on them go on the primary display. If this happens, you can plug only your primary monitor in the UPS and the other two in a normal power plug.