I recently bought another 2 monitors to achieve a 3 monitor setup. I had a dual monitor setup for the longest time between an HDMI and DVI port. I bought a display port to HDMI converter and plugged it into my 3rd monitor. I tried to extend the display onto the 3rd monitor and it did not work.
I have 2 HP 2311 23" Monitors and 1 Dell ST2220M 21" Monitor, all of them reach up to 1920x1080 in resolution.
When trying to extend the display to the 3rd monitor in the "Screen Resolution" screen through Windows, it comes up with the error message "Unable to save display settings." I then tried to do it through AMD's VISION Engine Control Center and when I attempt to extend the display to the 3rd monitor, it comes up with the error message, "To extend the desktop, a desktop or display must be disabled." and gives me the 2 options to "Continue" or "Cancel". If I do indeed continue, I just disable one of the two monitors already connected, and it just swaps places with the 3rd monitor. Basically, the 3rd monitor works perfectly fine, but I am only allowed 2 monitors to be used at one time.
I have also updated my drivers, but nothing has changed.