The monitors I am using are Dell 22" E228WFP (so a 2008 year model). I only get monitor out of range on the monitor that is plugged into the GPU that is only using one output, it matters not if I am using this output from the Top or the Bottom card, it matters not if it is the Left, Middle or Right monitor that is plugged in; it is ALWAYS the monitor that is plugged into the card that is only using one output.
I have switched out one of the Dell monitors for a 'spare -newish' 22" panel that I have lying around and it is now currently plugged into a GPU that is only using ONE output and I DO NOT GET monitor out of range?
Now it is clearly NOT 3 dead Dell 22" monitors, so I'm guessing it has something to do with the strenght of the signal when reporting the EDID back to the GPU?
P.S Same DVI cables used in both setups; and though my Dell Monitors are the same the DVI cables are NOT; so I can rule out this being a cable issue (in regards to the Dell monitors).