Someone just bumped this, simple way is to use Uniengine Heaven or Valley and use Sapphire Trixx to overclock, as Trixx is the only thing that allows me to change voltage. got it to 1120MHZ core with standard voltage.
If the card you have bought has an factory OC'd version, you can generally jump straight to those settings and go from there. Hardware wise both cards should be the same.
Also in general, a higher core clock = better performance than a higher the memory clock. So if you have an unstable clock, decrease the memory more than the core. I think the ratio is 1Mhz on the core = 4Mhz on the memory in terms of performance boost. Don't hold me to that though.
That NCIX Tech tips Video is very good, I followed that and I am enjoying a fairly good overclock.
Just one caveat, for some reason I didn't get any artifacts or issues running Furmark (or MSI's Kombuster) with a bad overclock.
You will have to play games or use 3D Mark11 to ensure you have a stable overclock.
Though Furmark is good for getting worst case scenario temperatures.