The chaps over at HotHardware have posted a review on the ATI Radeon HD 5970 Dual-GPU Powerhouse. Here's a taster:

Summarizing the ATI Radeon HD 5970's performance couldn't be any easier. The Radeon HD 5970 is simply the fastest, most powerful single graphics card available today. The Radeon HD 5970 offered better performance than every other graphics card we tested, regardless of the game or application. In comparison to other multi-GPU solutions, the Radeon HD 5970 falls in-line right about where you'd expect it to, considering its specifications. It's about on par with, or slightly ahead of, a pair of Radeon HD 5850 cards in CrossFire, but behind a Radeon HD 5870 CrossFire configuration.

Not only is the Radeon HD 5970 the undisputed performance leader, but it is also one of the most feature laden graphics cards currently on the market. With its dual Radeon HD 5800 series GPUs, the Radeon HD 5970 fully supports DX11 and ATI Eyefinity multi-display technology, and also sports the latest UVD engine, and has some of the best in-game image quality of any graphics card. On top of that, the card is highly overclockable, and despite being powered by a pair of the fastest GPUs out there, its power consumption characteristics aren't all that off the chart. Strictly speaking in terms of features and performance, the ATI Radeon HD 5970 currently has no rivals. Until you start pairing up multiple single-GPU powered cards, that is.

About the only downside to the Radeon HD 5970 is cost. The first wave of Radeon HD 5970 cards due to hit etailers today carry a hefty $599 MSRP. In light of its performance and current prices for competing products, $599 is certainly justifiable for the Radeon HD 5970, but we'll miss the days of sub-$400 flagship graphics cards--thank you Radeon HD 5870.