1920×1080 vs. 1920×1200 monitor for gaming with GTX 760 2GB

[leftisthominid]

My HU196D 1280×1024 monitor, is dying, and thus I need a new monitor (i.e., whenever my computer is off and it is plugged in the power light turns red and the screens blinks different colors).

I have been wondering about whether to go with 1920×1080 vs. 1920×1200 with the replacement, and I have a few questions.

How much more graphically intensive is 1920×1200 relative to standard 1920×1080 (for context, the most intensive games I will be playing on it this year will be Assassin's Creed Unity). I'd like to keep my games on high/ultra.

Also, how much of problem does letterboxing become (i.e., how much do developers support the resolution vs. force 1080p letterboxing)

CPU: AMD FX-6300 3.5GHz 6-Core Processor
Motherboard: Asus M5A99FX PRO R2.0 ATX AM3+ Motherboard
Memory: G.Skill Sniper Series 8GB (2 x 4GB) DDR3-1866 Memory
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive
Video Card: EVGA GeForce GTX 760 2GB Superclocked ACX Video Card

 

[rockie_]

i prefer 1920×1080 as it is standard and hope there would be no need of the GPU to re-calculate everything .