To overclock today we are using the latest V4.0.0 of MSI's Afterburner based on the excellent Rivatuner.
There was plenty of headroom available on this core. We pushed the core from 1,051 mhz to 1,284mhz before instability would occur. The Boost Speed was running at 1,411mhz. This translates into a very impressive 22.1% overclock. We have to point out that not every card will overclock to the same level as engineering tolerances will vary from card to card.
Still, all said, it is clear there is plenty of overclocking potential available on the OcUK GeForce GTX 970 ‘NVIDIA 970 Cooler Edition'.