I only able to get 8 MH/s ETH with my Gigabyte GTX 970 regardless the miner I use. And every time I start mining I get "PerfCap Reason:VRel" in GPU-Z while the "Power Consumption" is around 45% TDP. Most people get from 14 to 23 MH/s on GTX 970
Windows 7 64 bit sp1
miner the latest version
NVidia Drivers 388