The AMD Radeon HD 7000 adventure started last year with the Tahiti chip. With 4.3 billion transistors it is the largest, most complex and fastest out of the three Southern Islands GPUs that AMD has released in the last few months. Tahiti contains 32 compute units with 64 shader units each, which makes a total of 2,048 shader units. The GPU is linked via a 384-bit bus with the memory.
The Radeon HD 7970 is fast enough to be able to run most games in Full HD resolution on max settings. If you use three monitors in EyeFinity mode you will have to sacrifice some quality, or invest in a second card. In the meantime, Nvidia has launched an alternative in the form of the GeForce GTX 680.
On the 7970 all 2,048 shader units are enabled and the GPU runs standard at 925MHz. The 3GB of GDDR5 memory runs at 1,375 MHz. Radeon HD 7970 cards come with single DVI, HDMI and two Mini-Displayport connectors. Two Crossfire connectors make it possible to combine three or even four cards in Crossfire configurations. An 8-pin and 6-pin power connector provide up to 300 watts of power.
The 7950 is a step below the 7970. Only 1,792 out of the total 2,048 shader units are enabled - a decrease of 12.5 per cent. The GPU clock frequency is 800MHz and the memory is also somewhat slower at 1,250MHz. Because its TDP is lower, the 7950 only has two 6-pin power connectors. It's about 15 per cent slower and about 20 per cent more affordable than the 7970, which means a slightly better price/performance ratio.
The ASUS HD7950-DC2T-3GD5 has an even more extreme version of the DirectCU II cooler we've encountered on previous 7850 and 7870 cards. The card completely fills three slots, and really needs a fourth to be able to have some room to take in air. The card is standard overclocked to 900MHz, and 100MHz beyond that. You can read the rest of AMD Radeon HD 7950 / 7970 round-up on Hardware.info.