Overclocking And Performance
We wanted to figure out just how far the Radeon HD 7970 Super Overclock's Windforce 5X cooling solution would let us overclock AMD's Tahiti GPU.
Our GPU achieves an ASIC score of 66.7 in GPU-Z, which isn't very good. But we managed to overclock it well anyway. Using 1.25 V, we managed to hit 1250 MHz. At 1.3 V, that number increased to 1300 MHz. Both values are stable for long-term gaming and under our stress tests. The memory was stable up to about 1500 MHz. We started running into problems (including lock-ups) at 1550 MHz.
If you push your GPU to 1.3 V, then you really want to retain the card's default fan speed profile. Our custom configuration resulted in temperatures as high as 90 degrees Celsius. We discovered that our noise-optimized profile does work well at 1.25 V or less, though.
We’ve already spent plenty of time benchmarking AMD's Tahiti GPU, so we didn't need to run many tests to know where Gigabyte's Super Overclock card places. Really, it's only necessary to see where the stock 1080 MHz clock rate lands, along with the overclocked frequency of 1250 MHz.
Once you exceed about 1100 MHz, overclocking yields diminishing returns. Performance continues to increase at higher clock rates, but the ratio between faster frame rates and power consumption drops, negating the reason to push any higher.
It makes sense that Gigabyte's Radeon HD 7970 Super Overclock has a stock GPU clock of 1080 MHz. The one reason to push up to 1250 or 1300 MHz is benchmark bragging rights. But the speed-up won't make much difference in real-world gaming.