Yes the nVidia submitted kernel is expected to run 10-20% faster than Dave Andersen's kernels.
*sigh* I was almost hoping that was not the case. Now In good consonance I can't leave it be and only hash @ 500 kh/s a card.
Back to fucking this some more.
500 is fairly good on a Titan without overclocking. I've got my solo titan at 620 with +155 Core -502 Mem, try it.
Is that using the latest cudaminer? What kernal settings are you using?
Yes, latest version cudaminer, tried both x64 and x86 versions, same within a few khash of each other.
Settings are: -m0 -l T5x24 -i 0 -H 1 currently, although I have tried different values and none seem to make much, if any, difference.
I was also in the same boat after receiving my 750ti and not being able to break past 275ish until I started getting really aggressive with memory clocks. From my experience, the card starts hitting a power limit when the memory clocks get around 650 to 700 and while the overclock still seems stable then, the core overclock is reduced the more I push the memory.
My current working settings are +75 core +650memory along with -l T5x24 -H 1 -i 0 -m 1 and it gets me about 335-345khs +/-15 with less than 0.5% rejects. I only have one card running on the main 16x slot and the model is the EVGA ftw acx edition with the extra 6pins power connector.
Good luck, I hope you get your 300+ out of your card.