I have a 780 and use:
cudaminer.exe -i 0 -l K42x6 -C 2 -H 1 -o

Use it on x86 for a ~5% boost over x64

My 780 is water cooled so max temp after 20 hours was 45c

Non overclocked - 330Kh/s
Mild overclock - 360Kh/s
Max overclock - not tried yet but 400 Kh/s should be obtainable without issue.

This is my gaming rig, mining is just something it'll do at night time and when I'm out.
only sees a max of 10% CPU so everything is responsive still so may keep it mining all the time unless I'm playing a game.

I know an AMD card would be better for mining, but gaming is still priority so I'll stick with Nvidia.