I found why the NVIDIA GTX 970/980 shows such bad performance in mining (one of the reasons).
When running 3D games it enters P0 state (highest performance), when running Miners (CCMiner) it enters P2 state only. Specifically, the core goes to P0 but memory stays at P2, which means the memory never goes past 3000Mhz (6Ghz effective). So you're stuck with +-500hash.

Here's how to fix this:

1. download NVIDIA Inspector 1.9.7.3
2. click overcloicking
3. choose Performance Level[2] - (P2)
4. Click top right corner - Unlock Max
5. Move memory slider to 4000Mhz to start with (stable for me!)
6. Run your normal MSI Afterburner Precision X and set your OC clocks for CORE
7. Run ccminer and enjoy your new kickass hash... well not really kickass, but I'm getting +-625 hash now. Power usage in MSI afterburner howers between 66-67%, so knowing TDP of 160W the card uses around 105-110W 625 Hash! Bingo.

You welcome

P.S. This is for the GTX 980 obviously

P.P.S. For whomever is interested - this also makes the card get 7600 Khash in X11 mining without any CCminer tweaks, just 1500core8000mem settings and +0.075volt