I believe most have said you cannot 'SLI' two cards together and mine with them, so may want to work that into the equation or check into it further.

I believe the computer only sees SLI'd cards as a single unit, so only the first one would mine. I haven't done it or even tried, but I swear I read that someplace.

Good luck!

You are right. Sli is useless for mining. Hence why we use 750Ti's which can not do sli.
Not the only reason but i had to mention it

ooo and for anyone interested, i just boosted my MSI GTX 750Ti's to 1.4GHz and their running stable mining groestl.
Right now the increase from 1.3GHz to 1.4GHz and made a large improvement from
3.1MH/s to 3.4MH/s, all with an increased power load of 2W!

so to state, each of my cards now considers 2w more power, however produces almost 300khash/s more. So a 9% improvement for a 2% power increase. And the shares being submitted seem to be more stable aswell. If it gives stability issues i will be sure to let you all know. Performance with the new groestl release when its out will be very interesting. i wonder if overclocks will keep.

Thats a question actually, have you noticed an increase/decrease in TDP under the un-released groestl code? As if you havent, overclocks should remain good, and if you see triple performance, my overclock could get triple benefit (0.9MH/s) on each card

What MOST people can expect:
750 = 260khs

750ti = 300khs

I can likely go more on the 750s, but my 750ti's seem to max at about 305-310 now with the newest cudaminer and high overclocks.  Previously I was only able to get 288-295 consistently.

1,560khs for a 6x750 rig at about $720 in gpus (ones i got were $120)

1,800khs for a 6x750Ti rig at about $900 in gpus (@$150, mine were $165 on average though, so $990)

**Also keep in mind the 750s are supposed to use less power and I've never tried modifying the bios at all**

On your Config take a alook at reducing the "SMX" number:

ex. -l K7x32

You can try dropping the 7 to something lower. This can sometimes help. Some games just can't really deal well with sharing gfx. BF4 or BF3 are a great example... my Titan has more then enough power to play them but not with CUDAMiner running at even super low settings. While League of Legends I can just use my normal config and switch it to  -i 0 and boom frame rate loss but well within playable.