Get MSI afterburner 1.6.1, go into settings and unlock the voltage tweak option, and then increase the voltage slider.
You need to increase the voltage to get to 850 Mhz and beyond, aroun 1.050 - 1.087 (which is the max allowed). The stock voltage is 0.975, but the Asus / MSI / Gigabyte can easily handle more.
Gotta try furmarking it to test for stability and temps. The other guy with the palit is getting 80 degrees at 800 Mhz.
Running it now it is hovering around 70-72.c @ 880 mhz... I do have a 120mm fan sat on the side of my case blowing directly on to it so maybe that is helping....