HIS IceQ 7870 Overclock

MSI Afterburner is a great program for overclocking. No reboots, BIOS, or any fancy stuff required.

As for the overclocking, I'd take a decent leap and then test stability for a while. If it works out, try taking baby steps towards upping it some more.

I am running an HD 7870 by Gigabyte and have it running stable at 1175MHz core and 1450MHz memory. That's not to say you will see the same stability and temperatures on the HIS version, although it is by all reports similar in quality to the Gigabyte version.

I would suggest starting out by just increasing the power limit to +20% and going with 1150MHz core and 1350MHz memory. If that works out well, try unlocking the voltage settings in the menu and bumping them to 1300 (assuming the IceQ caps at the same mine does), then trying increasing by 25MHz, one setting at a time, and testing stability / temps again.

Test using FurMark or MSI Kombustor on your native resolution. 2 hours per test is generally recommended, but I've found that about 15 minutes finds your temperature peak and just jumping right into gaming will give you a good idea of stability. If you see graphical anomalies or crashing, you need to clock it back down a bit and try again.

As for the temperature, 85-90c is the peak safey limit, but I'd personally keep it lower than that. My card peaks at 71c on the overclock, which is well within reason.

If you must, set the fan speed on manual via Afterburner and keep it high enough to cool the card down.

Good luck! Well, it's easy, you won't need luck. Have fun!

Oh, and you have good taste in motherboards  

I use iTurbo which comes with the HIS card. I was able to get a 1100/1350 overclock without any voltage. Also, i would not recommend starting at 1.3v, id keep adjusting your clock up by 25mhz at a time, and then bump up the voltage as needed. That being said, my card will run 1200/1375@1.3v, but that voltage seemed high to me, so i lowered mine down to a 1175/1350@1.275v overclock respectively.

As for stress testing, best one ive used is 3dmark for stress and furmark for looking at temps. But honestly, nothing can beat play games like crysis for TRUE stress testing.

Probably a good call to watch the voltage. Your cards are different than mine and may not react the same way. I also didn't know much about voltage tweaking when I first replied to this, but I have since done my first CPU overclock and now I have more of an idea of what to watch out for. Just try small steps to see what works, until you find a comfortable spot to stop.

Did you also increase the board power limit? or just change the VDDC?