yes it possible to change the core and the memory with the zero state, try this guide to have more hash http://cryptomining-blog.com/7341-how-to-squeeze-some-extra-performance-mining-ethereum-on-nvidia/
Thank you very much for this Nvidia guide!
I was running nvidia-352 drivers and cuda 6.5 and it didn't work because of an "unknown error". So I installed the newest nvidia-361 drivers (and apt-get uninstalled cuda). Now every command didn't cause any errors but if I enter into the terminal for the 750Ti "nvidia-smi -ac 3004,1476" nothing happens if I look into the nvidia settings and at my hash rate, which is still 5.2 MH/s with the cuda version (cmake -DBUNDLE=cudaminer -DCOMPUTE=50 // ethminer -U) of Genoils ethminer.