AMD has enjoyed a terrific run with the Radeon HD 5000 series as it took Nvidia no less than six months to counter with its initial Fermi products. It's been a year since we reviewed the Radeon HD 5870, calling it a "real winner, and possibly one the best graphics cards we have ever reviewed in this price point." Within five months of releasing its first DirectX 11 GPU, AMD launched another eleven graphics cards ranging from affordable to the ultra-expensive.

On the other side of the fence, the GeForce GTX 480 and GTX 470 arrived months later and weren't nearly as well accepted as Nvidia hoped. Some two months after entering the DirectX 11 market, Nvidia tried to crank up the heat by unleashing its GeForce GTX 465. Sadly, the card was a flop and it took them six more weeks to finally make headway in the DX11 GPU market with its GeForce GTX 460.

Arriving at $200 (currently $170), the GTX 460 768MB bested the existing Radeon HD 5830 while simultaneously threatening the more affordable Radeon HD 5770 cards. Meanwhile, the 1GB version of the GTX 460 has sat at $230, diminishing the Radeon HD 5850's value.

Now on the prowl for three months, the GTX 460 has forced AMD to cut prices but we still feel the GeForce GTX 460 is better than the immediate competition. That poses a serious challenge to AMD, which vowed last year to keep on top of Nvidia throughout 2011 – an unachievable task without some kind of radical overhaul. Today marks that overhaul, with AMD launching two new graphics cards designed to tackle the GTX 460. Known as the Radeon HD 6870 and 6850, AMD's fresh offerings might not be quite what you think.

Given the naming scheme, you'd expect the new cards to replace the existing Radeon HD 5870 and 5850, but that's not the case. Instead the new Radeon HD 6870 and 6850 are being presented as the new mid-range offerings in AMD's line-up with a suggested retail of $239 and $199, respectively – suspiciously close to the 1GB and 768MB GeForce GTX 460.

The year-old Radeon HD 5870 and 5850 will be axed next month when AMD launches the Cayman-based Radeon HD 6970 and 6950 graphics cards. While the existing Radeon 5700 series is expected to take over the lower-end affordable graphics sector.

We expect the Radeon HD 6870 to be slightly slower than the 5870, while the Radeon HD 6850 should be slower than the 5850, just don't pay attention to the tricky naming. The new cards supposedly improve upon Radeon HD 5000 series with better DirectX 11 and enhanced display support, but perhaps most importantly they are set to offer a better value than Nvidia's GTX 460. Read on.