Change Screen size

I have a 27 inch screen, awesome for watching movies on my room, but a bit too big for playing games,working or surfing... I have a Radeon HD7850 card, in Catalyst Control Center(CCC) I can change the screen size so that my 27inch screen is not completely filled, but

1)can I change the screen size even more, because CCC caps at 10%(underscan setting)
2)in CCC there is an option to save a preset, but it seems to be unable to remember underscan setting, am I doing something wrong, or is it really impossible to do this

 

What screen size are you using ?

 

90% filled screen, this is the minimum value I can set In CCC

 

Your screen size should be (1920x1080 ) Is this your screen size, If not, Then there is your Problem,,