Two same monitors, resolution on second lower.

[FinSa]

I have two BenQ GW2450HM monitors, my graphics card is a Sapphire Radeon HD4870X2 and the monitors are plugged into DVI spots, but the other one is a belkings DVI-HDMI cable.

But as you can see, it for some reason does not use the whole screen.

 

[CGurrell]

Go to AMD Catalyst Control Centre (If it's available with that GPU) -> My Digital Flat-Panels -> Scaling Options -> Change to 0% (Or whatever fills your screen properly)

Sometimes when using HDMI (or a HDMI adapter) the PC thinks the monitor is a TV so has to under scan to make sure everything fits (TVs naturally overscan due to how images are received through an ariel/sattelite/cable)

 

[geofelt]

Does the problem move if you switch monitors?