GTX 9XX cards need a really old driver to run on windows, check the driver on the OP and make sure you run the miner in the cuda6.5 folder..
I run mine on linux to avoid all the hassle..
Im using latest drivers and run miner from EthDcrMiner64.exe im the root folder (not cuda6.5 or cyds7.5) and have ~18mh/s on old and new drivers. Im doing something wrong?

I mean u sayin' that 900 series needs old drivers and cuda6.5 *.exe file, but im fine on default *.exe and latest drivers.