Power, Temps, Noise and Overclocking
As with the Radeon 6900 series and GTX 500 series the 7900 series performs power management in a different way to older cards so we have changed the way we test power and temperature levels in our reviews. For idle power we list the full system use at the wall after sitting at the desktop with no activity for 5 minutes. Load power is the highest reading we saw for the full system when testing during this review. Temperatures are taken in the same way. Noise levels are taken after a period of prolonged gaming in a scenario which applied maximum load to the GPU.
When listing the key differences between the 7970 and 7950 we noted that one of them was power use. That proves to be the case here as the Sapphire card, regardless of the BIOS used, runs around 60w lower than the 7970 OC… and way, way lower than the GTX 580 OC at 438w. The thermal performance is also better on the Sapphire 7950, it idles at 31°C at most hits 67°C when gaming with the lower speed fan profile. Move to the higher speed and we top out at 65°C but most impressively the card is still near silent at this level as the video below shows.
Sticking with the power and noise theme for a moment, as with our other articles on the 7900 we also need to note that one of the key 7950 series features is the advanced power management which has been implemented in Crossfire. In that mode AMD are able to send the second card to an ultra-low power state when idle and as shown below this means turning the GPU and memory to 0MHz.
As an added bonus to the second (or additional) cards minimal power use the driver also shuts down the fan turning the card into a silent model.
Moving to overclocking we get to take a look at Sapphires own tweaking utility, TriXX. TriXX is a free tool available from the Sapphire website which allows us to change the speed and fan settings on our card. It is a simple process and no more than moving a few sliders.
Using TriXX and the second BIOS profile with faster fan speed we were able to acieve a core speed well in excess of 1000MHz, further enhancing the performance of the card. Here are the 3DMark changes.
That’s a rather impressive score from the Sapphire 7950 OC but it is always useful to see how this translates into gaming performance and for that we re-ran the Battlefield 3 tests, here are the results.
There are two key things we can take from the above results, firstly that the 7950 at its maximum comes very close to 7970OC performance. Secondly that the increase in core and memory speed allows the 7950 to pull ahead of the GTX 580 OC in this test as well as opening the gap over the 6970 further too.
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