Overclocking

AMD has changed the way its card is overclocked with the HD 7970 3GB GHz Edition. Instead of increasing the clock speed, the overclocked speed becomes the card’s new boost target frequency. With that in mind, we were able to push the card to a boost core frequency of 1,175MHz, alongside a memory frequency of 1,625MHz (6.5GHz), although with no way to monitor the clock speed in real-time, we had no idea how often the card was boosting to these speeds.


The result was apparent though, as the minimum frame rate increased by 10 per cent from 39fps to 43fps in Battlefield 3 at 2,560 x1,600 with 4 x AA. In ARMA 2 we saw a slightly lower 8 per cent increase, with a minimum frame rate of 56fps, up from 52fps.

Conclusion

We’re in two minds regarding the HD 7970 3GB GHz Edition. Clearly the higher clock speeds and performance improvements of Catalyst 12.7b has made AMD’s high-end far more competitive; it’s certainly no longer a case of which Nvidia to buy any more and the GHz Edition underlines this. In ARMA 2 and Dirt 3 the GHz Edition is now the fastest single GPU card, while in BF3 it’s too close to call, although Skyrim remains a fly in AMD’s ointment.


However, AMD’s decision to release this card is odd in itself. There are already HD 7970 3GBs with factory overclocks very close to that of the GHz Edition and with a 5-10 per cent tweak to the power state it’s not difficult to overclock a standard 7970 3GB to clock speeds in excess of those offered by the GHz Edition. The launch is also an extremely cold one; we’ve no word yet on when this card will hit retailers and only a USD price of $400 to go on. Considering pre-overclocked and custom cooled HD 7970 3GBs can be found for £350, a price of £400 should be expected, still cheaper than the £420 that GTX 680 2GBs current sell for.

The choice isn’t black and white though. While the 7970 3GB GHz Edition is the fastest single GPU card when compared to the GTX 680 2GB across all of our benchmarks, it’s also 60W more power hungry and much louder under load too. It’s not as big a gulf in power consumption and noise as we saw with the GTX 480 1.5GB vs. the HD 5870 3GB two years ago, but the situation is certainly reminiscent.

Without solid pricing information, we’re reticent about making a final judgement, although a price of £400 seems likely whenever the GHz Edition finally hits shelves. If this proves true, we’d still choose the 680 2GB thanks to its lower power consumption and noise levels, with pre-overclocked HD 7970 3GB’s instead looking the more attractive option. One thing’s sure though; picking that new graphics card just got a whole lot tougher.