I've been experimenting with the lookup gap with CudaMiner and I came up with a few Scrypt-Jane settings at N14 that might work better for those with a 750ti. I'm using both of these configs as each appears to work best with the rig its on. One has 4 ACX cards with the 6pin adapter and the other has 3 ACX cards- the rest are the non-ACX cards that are dependent on the powered risers.
I managed a 20-25% increase in output than with the best I can get with the default lookup gap of 1, going from around 2.6-2.8 to 3.1-3.6 mh/s each card. It's takes quite a lot longer to autotune with the higher lookup gaps, but it appears that it is worth it to find that sweet spot for kernel configuration. A lookup gap of 3 or 4 seems to bring the most gains.
Each rig has a Asrock PRO H81 mobo, 4GB RAM with USB 3.0 Powered Risers and 550W PSU, running on Ubuntu Server 14.04 with Cuda Tools/Library 6.0.37 installed. All cards with stock tuning. I tried flashing a overclock modded bios on each with a hefty overclock and a moderate overclock and the stability loss wasn't worth the gains. I might revisit this again though.
cudaminer -L 3 -l t5x20 => 19.5mh/s (6 card rig)
[2014-10-04 12:14:24] Stratum detected new block
[2014-10-04 12:14:24] GPU #1: GeForce GTX 750 Ti, 3.19 khash/s
[2014-10-04 12:14:24] Temp: 51C Fan speed: 44% Power: N/A
[2014-10-04 12:14:24] GPU #3: GeForce GTX 750 Ti, 3.21 khash/s
[2014-10-04 12:14:24] Temp: 53C Fan speed: 46% Power: N/A
[2014-10-04 12:14:24] GPU #0: GeForce GTX 750 Ti, 3.61 khash/s
[2014-10-04 12:14:24] Temp: 52C Fan speed: 44% Power: N/A
[2014-10-04 12:14:24] GPU #4: GeForce GTX 750 Ti, 3.16 khash/s
[2014-10-04 12:14:24] Temp: 52C Fan speed: 45% Power: N/A
[2014-10-04 12:14:24] GPU #2: GeForce GTX 750 Ti, 3.17 khash/s
[2014-10-04 12:14:24] Temp: 52C Fan speed: 45% Power: N/A
[2014-10-04 12:14:24] GPU #5: GeForce GTX 750 Ti, 3.18 khash/s
[2014-10-04 12:14:24] Temp: 44C Fan speed: 42% Power: N/A
[2014-10-04 12:14:34] GPU #2: GeForce GTX 750 Ti, 3.22 khash/s
[2014-10-04 12:14:34] Temp: 52C Fan speed: 45% Power: N/A
[2014-10-04 12:14:34] accepted: 122/122 (100.00%), 19.56 khash/s (yay!!!)
cudaminer -L 4 -l t35x4 => 19.7mh/s (6 card rig)
[2014-10-04 12:15:18] Stratum detected new block
[2014-10-04 12:15:18] GPU #3: GeForce GTX 750 Ti, 3.30 khash/s
[2014-10-04 12:15:18] Temp: 53C Fan speed: 45% Power: N/A
[2014-10-04 12:15:18] GPU #2: GeForce GTX 750 Ti, 3.37 khash/s
[2014-10-04 12:15:18] Temp: 53C Fan speed: 45% Power: N/A
[2014-10-04 12:15:18] GPU #4: GeForce GTX 750 Ti, 3.37 khash/s
[2014-10-04 12:15:18] Temp: 58C Fan speed: 49% Power: N/A
[2014-10-04 12:15:18] GPU #0: GeForce GTX 750 Ti, 3.39 khash/s
[2014-10-04 12:15:18] Temp: 53C Fan speed: 45% Power: N/A
[2014-10-04 12:15:18] GPU #5: GeForce GTX 750 Ti, 2.95 khash/s
[2014-10-04 12:15:18] Temp: 54C Fan speed: 46% Power: N/A
[2014-10-04 12:15:18] GPU #1: GeForce GTX 750 Ti, 3.32 khash/s
[2014-10-04 12:15:18] Temp: 54C Fan speed: 45% Power: N/A
[2014-10-04 12:15:25] GPU #1: GeForce GTX 750 Ti, 3.39 khash/s
[2014-10-04 12:15:25] Temp: 54C Fan speed: 45% Power: N/A
[2014-10-04 12:15:25] accepted: 75/75 (100.00%), 19.76 khash/s (yay!!!)
I also messed with YAC a bit. The best gains there were at a lookup gap of 4 and also about the same at 8, with the lower lookup gap taking less wattage at the wall.