At US $599 a piece, two Radeon HD 5970 accelerators should typically set you back by $1200. You will also need a motherboard with two PCI-Express slots, which supports ATI CrossFire technology.
Fastest setup possible
Support for DirectX 11, DirectX 10.1
Some things just look better in pairs™
Low idle power consumptions of each card makes overall idle power draw comfortable
Excusably quiet in idle
Support for software based voltage control
Support for AMD EyeFinity Technology
Native HDMI & DisplayPort
Improvements to integrated HDMI audio device
High price, really!
Fails several game tests at 2560x1600
Not useful for resolutions lower than 2560x1600
Requires a CrossFire supportive motherboard with two PCI-Express slots
Massive heat output
DirectX 11 won't be relevant for quite a while
No support for CUDA / PhysX
It sure isn't the most sensible thing to spend $1200 on two graphics cards, that dump about 600W of heat in your room when fully loaded, that barely fit inside your computer, and that make a quite some fan noise. But oh boy, the frames fly like you've never seen before! The "All Resolutions" performance summary graph simply doesn't do justice as HD 5970 CrossFire gets irrelevant, and CPU-limited in lower resolutions. 2560x1600 seems to be the only resolution where having a pair of these will allow you to splurge on eye-candy like never before. If you want to build the fastest rig money can buy then a HD 5970 CrossFire setup is what you need. Die-hard overclockers all over the planet will open their wallets and camp the online stores to get a pair of these, unfortunately supply will be limited. Should you not belong to the most extreme crowd of gamers or tweakers then it might make more sense to get a single HD 5970 or "only" a HD 5870 because these cards offer much better price/performance ratios. It should also be noted that the drivers do not seem to be in a fully finalized state yet. Three of our benchmarks failed to run at 2560x1600, which, for this kind of product, is the only resolution that really counts in the results. I am confident however that AMD will quickly address these issues in a future driver version.