A couple critical notes before we proceed: as always, mileage will vary when overclocking, so be vigilant in monitoring temperatures and be sure to always test for stability after each incremental change. You can use FurMark or Kombustor, though there is some question about their suitability, so you could instead run 3DMark and see if it can pass a few looped tests for stability, but be sure to log and monitor the resulting temperature.
HIS offers the iCooler utility to monitor and adjust the clock speeds, voltages, and fan settings. The software is rather straightforward, no advanced graphing features, but it gets the job done. Our only beef with it is that the size of the GUI remains utterly massive, far bigger than necessary. We’ve offered some feedback to HIS regarding the layout and size, perhaps we’ll see some revisions in the future that will take up less visual real estate.
More importantly, perhaps, is this card somes with the HIS iPower feature, which allows for voltage increases to the card’s main components. As you’ll see below, this is why we were able to achieve such great overclocking results. Without any voltage increase, you won’t be able to maintain stability, and therefore your clocks won’t be as high. Any premium card nowadays that wants to cater to the enthusiasts needs a voltage tweaking feature, in our opinion. In addition, the card features an extra PWM in an 8-phase power design (6+1+1), whereas the reference design is 5+1+1, so this will provide some added stability and longer life for the HIS card.
iPower is not to be confused with the Boost Clock, which is essentially the overclock speeds provided out of the box. Keep in mind that HIS offers several different 7970 models, each of which are a bit different in terms of speeds and features, so be sure to check them out before potentially deciding which card to buy.
With that out of the way, we settled in for some overclocking of the core and memory clocks, juiced up the voltages, and achieved the following result:
We topped out at speeds of 1205/1675MHz, which is an impressive 15% increase on the core, while the memory still has plenty left in the tank as well.