Hey man! I just setup a brand new rig an hour ago with 5 cards running at 735kh/s (same model as yours!)

Here's the config:

-I 13 -g 2 -w 256 --lookup-gap 2 --thread-concurrency 11200 --gpu-engine 1060 --gpu-memclock 1500 --gpu-powertune 20 --shaders 2048 --temp-target 69 --auto-fan

I tried a million different settings and found that this model maxes out at these settings. Moving the clock up kills the hash and changing the TC to 8192 also lowers it.

Try it and let me know how it goes! If you can squeeze out any more hash out of it please report back.