Bad 2D performance DUAL 690's

Hi all....hoping someone may have some advise.

I just put together a new system...as below...

Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz
Asus RAMPAGE IV EXTREME
Gskill 16G DDR3 2400
2x Palit GeForce GTX 690
OCZ-AGILITY3 (120GB, SATA600, SSD, NCQ) : 112GB
Corsair Force GS (240GB, SATA600, NCQ) : 224GB

Thermaltake Toughpower TP1200


Microsoft Windows 7 Ultimate 6.01.7601 (Service Pack 1)
Platform Compliance : x64


My problem lies with performance once I setup 2D surround mode on 3x Samsung 27' SA950 monitors USING BOTH CARDS.

What i mean is that when using only one graphics card, games running in surround mode at 5760x1080 run at a constant 50-80 FPS.

Once I setup both cards QUAD SLI in surround mode at same resolutions and settings....frame rates drop to around 22 and the sound stutters. Noticeable small pauses and lag when playing.

I am failing to understand why, or how to solve.

Any ideas??

Thanks in advance.