http://www.pcgamer.com/you-might-not-be-able-to-overclock-nvidias-geforce-gtx-1070-ti/

We are fairly confident that Nvidia is readying a GeForce GTX 1070 Ti graphics card that slip into its product lineup between the non-Ti variant and the higher-end GeForce GTX 1080. However, if you are hoping to squeeze out GTX 1080-like performance through overclocking, you might be in for a rude awakening—the latest rumors suggest Nvidia is locking the frequency on the GTX 1070 Ti.

Bearing in mind that none of this is official, the rumor traces back to two sources, and the reports are slightly conflicting. Eteknix says it heard from an "industry insider" that the GeForce GTX 1070 Ti will not support overclocking in any way, shape, or form. "In addition, we've been informed that Nvidia will not release any reference cards and all AIB (add-in-board) partner cards will be locked to the same speeds. However, price and aesthetics are expected to differ across partner cards," Eteknix says.