Radeon HD 7970 and 7950
AMD’s current flagship is the Radeon HD 7970, using the Tahiti GPU. The GPU contains 2,048 shader units and runs at 925MHz, which according to AMD results in a maximum processing speed of 3.5 Teraflops (3.5 trillion floating point operations per second).
The card has 3GB GDDR5 memory that is connected via a 384-bit bus to the GPU. The combination of a high clock frequency (1,375MHz) and the wide 384-bit bus makes 5.5Gbit/sec memory bandwidth possible.
The video card has a dual-link DVI port, two mini DisplayPort sockets, and an HDMI connection. A maximum of six monitors can be connected (EyeFinity). To enable customers to connect three affordable DVI monitors without spending more money, AMD requires its partners to include an HDMI-to-DVI and a DisplayPort-to-DVI converter with the Radeon HD 7970.
The maximum power usage of the card is 300 watts, according to AMD. It also claims that power usage on just the Windows desktop is less than 15 watts, dropping below 3 watts when idle (with the screen turned off). The card has 8-pin and 6-pin cables to power the GPU.
Of course you can also use the Radeon HD 7970 in dual-, triple-, and quad-CrossFire configurations. On top of the card you find two CrossFire connectors. You can also choose which BIOS you would like to use. Overclockers can easily flash or modify one of them, while the other functions as a safety net should something go wrong. The video card has a newly designed cooling system, building on the existing wind tunnel principle.
Radeon HD 7970 video cards are available from about £420. On average they cost around £445.
The Radeon HD 7950 is based on the same 28nm Tahiti GPU as the Radeon HD 7970, and they look exactly the same. There are, however, two main differences. The first is the number of shader units. The Radeon HD 7950 has 28 out of the 32 compute units enabled while the 7970 has all of them enabled. This results in 1,792 shader units for the 7950 compared to 2,048 on the 7970.
The second difference has to do with the clock frequencies. The GPU works at 800 MHz on the Radeon HD 7950, whereas the GPU on the 7970 does this at 925MHz. The memory works at 1375MHz compared to 1250MHz, respectively. One more difference, albeit small, is that the 7970 has 6-pin and 8-pin power connectors, while the 7950 has two 6-pin connectors.
Other than that both cards are identical. This means that the new card also has 3 GB of memory, connected via a 384-bit bus. There is one dual-link DVI port, one HDMI port, and two DisplayPorts. The PCB is identical, as is the cooler. The card is of course compatible with Crossfire configurations.
The Radeon HD 7950 video cards are clearly cheaper. You can already buy one for £340 and the average price is £370. The table below shows the similarities and differences.