Well............... i think i didn't catch your exact issue in the first place.
Not your fault.
If i undestand correctly now, you want to clone the 1200p monitor to the 1080p.
But, instead to keep the 1200p res. on the 1st display and pan/scan that resolution in the 1080p monitor, you get the reverse effect.
You get the 1080p res. cloned to your 1200p monitor, hence the black bars.
I think you should disconnect all extra monitors and start again.
Make the NEC 2690 your primary display first.
Then clone the 1200p res. to the Samsung UE46F5020.
Leave the Samsung 732N for last.
gigabyte X58A-UD3R rev.2, core i7 975 3.9ghz (stock voltage), windows 8.1 64-bit, corsair 12gb DDR3 1600mhz 7-7-7-20 RAM, xfx HD 5970 + gigabyte HD 5970 (950mhz/ 1100mhz), coolermaster ultimate 900w PSU.
AMD Catalyst 15.4 beta