Overclockers Club published a review on the NVIDIA GeForce GTX 1070 Overclocking
A quote from the article:
The best possible core clock speed/memory speed I was able to wring from this GPU was a solid 2050MHz to 2063MHz under load at the maximum reported temperatures. If I could keep the core temperature another 10 °C cooler, the card will run at 2126MHz all day long. Overclocking would not be used if it did not have an added benefit. With stock speeds on the GTX 1070 Founders Edition offering GTX Titan X performance for a fraction of the cost, you can do even better than Titan X performance in many games. Overclocking the GTX Titan X does even up the field, but it's amazing that for a potential AIB card price of $379, you cannot go wrong. Launching June 10, the GTX 1070 Founders Edition will be available for $449. Much like the GTX 1080, the GTX 1070 has got style, runs cool and quiet, and is tough to beat at the current pricing.NVIDIA GeForce GTX 1070 Overclocking Review @ OCC