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Today sees the launch of AMD's latest top-of-the-range DirectX 11 graphics card, the ATI Radeon HD 5970 (codenamed Hemlock). Like AMD's previous high-end cards, it uses two graphics chips housed on a single board and has an internal CrossFire interface to get the ultimate in performance. Since AMD's current top-of-the-range single-chip card, the Radeon HD 5870, is already one of the fastest in the world, this new card is sure to take performance to the next level. Shortly we'll see if it does but first, a bit of a history lesson.
For the last few generations of its graphics cards, AMD's strategy has been to create a chip that will compete at what it sees as the more lucrative mid- to high-end market of £200-£300, rather than the ultra high-end of £400+. It then uses two of the chips to create a single monster of a card to compete at that top-end. The same architecture is then used to design scaled down versions of the chip to create lower end cards. In contrast, nVidia has aimed its previous top-end chips much higher, thus creating much more expensive and faster single chip cards. This is still nVidia's strategy, as its latest 'Fermi' architecture proves.
The result of this is that AMD has had to bring its dual-chip cards to market simply to compete with nVidia's top-end single chip cards (not to mention nVidia's dual-chip cards as well). However, this time around we have a slightly different situation. While the HD 5870 still isn't the out and out fastest card - the nVidia GeForce GTX 295 and ATI Radeon HD 4870 X2 (both dual-chip cards) still trade places for top spot with it - it's the clear choice of the three due to its support of DirectX 11, its lower power consumption, and better compatibility thanks to its single chip (while CrossFire/SLI support is getting ever better, some games still have issues with these dual-chip solutions). As such, the need for AMD to release the HD 5970 is limited right now; it could easily sit back and wait for the HD 5870 to reap its rewards for a bit longer. Nevertheless, AMD has chosen to launch the card already so let's take a closer look.
The HD 5970 uses two Cypress chips mounted on a single board with 1GB of GDDR5 memory for each chip. The GPUs run at 725MHz while the memory is clocked at 1GHz (effectively 4GHz), which theoretically means this card will have performance that sits somewhere between two HD 5870s in Crossfire and two HD 5850s also in CrossFire - it has the same number of SIMDs as the 5870 but the clock speed of the 5850.
Physically the card is something to behold, at 12.2in (310mm) long and weighing 1.2kg, it is simply colossal. This immense length means the card overhangs the back of a standard ATX motherboard by 2.5in (6.5cm) and as such won't fit in many cases, so check there's space before opting for this card (incidentally, the ATX specification does allow for cards up to 13.3in long so AMD isn't breaking any rules here).
Conversely, by picking prime examples of its Cypress chips and keeping the clock speeds down, AMD has managed to keep the HD 5970's total power consumption to below 300W, so it only requires an 8-pin and a 6-pin auxiliary power connector, rather than two 8-pin connectors. This means it stands a better chance of being compatible with your power supply.