The processing and texturing power of the Radeon HD 7970 is up 40% on the Radeon HD 6970, while the memory bandwidth is up by 50%.
The reference Radeon HD 7970
For this test, AMD supplied us with a reference Radeon HD 7970:
The Radeon HD 7970 is the same size as the Radeon HD 6970: double slot and 27.5 cm long. Its cooling system is similar but has been developed slightly. The blower has longer blades to increase the airspeed and the vapour chamber block / radiator extends 1.5 cm further towards the connectors. Its extremity is therefore very close to the hot air extraction grill which has also been adapted to cover the full height of a PCI slot and it’s no longer necessary to send some of this hot air into the casing above the card. One of the two DVI ports therefore had to go, with the remaining one accompanied by an HDMI out and two mini-DisplayPort outs. An HDMI to DVI adaptor is supplied with the card.
The GPU is surrounded by a metallic structure designed to protect it and guarantee the rigidity of the packaging. Unfortunately this structure is slightly thicker than the die, which means that alternative cooling systems will have to be adapted to be compatible. Be very careful if you decide to replace the orginal cooler!
Probably for cost reasons, AMD has dropped the plate covering the back of the Radeon HD 6970 and 6950 2 GB. The design of the casing that covers the cooling system has however been modified to make it much more aesthetic than the one used for the Radeon HD 6900s, which had a rather austere look and a cheap feel. In general, we’re not great fans of glossy designs but here it has been carefully made with quality materials.
The PCB is not that different to the one used for the Radeon HD 6970, but the power stage has been revisited to make it more powerful, with better quality components though still with 6 phases for the GPU. This increase in power isn’t actually necessary and one of the six phases remains vacant. The design will however allow manufacturers who so desire to produce an overclocked model with more in reserve and it will also be possible to go from 8+6 pin power supply connectors to 2x 8 pins.
Two CrossFire X connectors are still available to enable tri and quad-GPU support and you still get the dual bios switch allowing you to return to the original bios.
Our card’s GPU proved quite cooperative when it came to overclocking and we managed to take it from 925 to 1075 MHz. This sort of gain (16%) is unusual on high-end GPUs. We did of course check to make sure that PowerTune wasn’t reducing the clocks by measuring performance in several games (in Furmark where PowerTune does kick in, we were able to get up to “1125 MHz”). At 1075 MHz, we observed a gain of 10% in Battlefield 3 and 14% in Anno 2070.