This is a tricky one to try and work out and I'm after some thoughts and assistance.
I have 3 monitors on my desk. These are connected by different connections to a work laptop and and my desktop pc.
The desktop pc has an nvidia geforce GT710, with a hdmi, dvi and vga outputs. It runs windows and Manjaro linux. When it boots it randomly doesnt display any output on the main monitor, a 32 inch acer. The monitor sees a signal as it keeps cycling around the options and wakes from standby, but want fix on an input.
You can get the 2 other screens to wake up once the OS is loaded by blindly logging in, then fiddling with the display settings for the 32 inch screen and setting different resolutions and modes it will eventually at random wake up.
This has been going on for some time and I have changed the graphics card, all the cables from the card to the monitors, which output from the graphics card each monitor is on. All to no avail. I have reinstalled OS's numerous times.
The work laptop always wakes up first time every time.
If you have only one monitor plugged into the graphics card it will usually work fine.