Radeon HD 7970 Vs. Radeon HD 7970 GHz Edition
We start off by testing both cards at 1050 and 925 MHz. Since our samples are completely stable at those frequencies, we didn’t have to touch the PowerTune slider at all. The new card didn’t throttle, either, yielding an ideal comparison. As before, we logged power consumption for 50 seconds, using a gaming workload this time.
The dotted lines represent one card running at the emulated clock speeds of the other. And the final analysis yields an interesting result: the older and supposedly less-refined card draws marginally less power at 1050 MHz. It does even better at 925 MHz, coming in almost 5 W under the GHz Edition board. Perhaps this is a result of AMD’s voltage-adding mechanism designed to keep Tahiti more stable at its boost frequency.
However, we’re still not applying a full load to either card. Our next test does just that by applying a compute workload that doesn’t trigger throttling.
Power draw is pretty similar between the two boards. The new card might do its job under the TDP ceiling defined for the original 7970, but AMD’s GHz Edition board definitely doesn’t offer more performance at the same power levels as its predecessor. If you want more speed, you have to use more power.