AMD Radeon HD 6950/6970: New high-end DX11

Originally scheduled for late November, the new high-end graphics cards from AMD we finally arrived, not without some delay. Remember that if AMD was first to introduce its second generation DirectX 11 graphics chip, it has made an unconventional way, by launching the first new mid-range reference ... it was late October with the release Radeon HD 6850 and Radeon HD 6870. Since nothing, and then radio silence that NVIDIA launched in early November its GeForce GTX 580, AMD delayed in extremis the release of its Cayman. Delay probably motivated by questions of matching performance with the new Cayman NVIDIA offers, an offer that has no doubt surprised by the performance gains achieved.

So in mid-December that AMD chose to commercially launch its Cayman, the codename of the new Radeon HD 6950 and Radeon HD 6970 to replace this time and for real, the previous Radeon HD 5850 and Radeon HD 5870. Overview of features and performance of new cards. While Barts, codenamed Radeon HD 6850 and Radeon HD 6870, enjoying a slightly redesigned architecture to face old Radeon HD 5800, the Cayman to inaugurate their full graphics architecture rethought. It starts with the observation that the old calculation units present in the SIMD engines were difficult to use at 100%. As a result, AMD revisits the arrangement of units: As with the Radeon HD 6850/6870, the heart of the chip is still divided into two main blocks each comprising units of execution which will perform the treatments on our various programs shading. Each of these two clusters is controlled by allocating a block orders to maximize the use of units, in that it remains close to what is done with the Radeon HD 5000 and 6000.

But even if we go back one level we see that each processor dispatch (the unit that distributed tasks) is connected to a separate graphics engine. The Radeon HD 6900 available then, and it's new, two graphics engines providing features include rasterization, assembly of the vertex and geometry without forgetting the tessellation. Thus, the Radeon HD 6900 have more resources in terms of geometry and can therefore work on two triangles per clock cycle with the possibility to charge 32 pixels per clock with dual rasterizer. Moreover, each graphics engine has a tessellation unit eighth generation. This improved to deliver even better performance thanks to the possibility of buffer (off-chip) some data. Recall that the units have tessellation support the subdivision of triangles: from a triangle calculated, the unit may subdivide it at will and without impacting performance in the thin-set geometric details and therefore richer image. If AMD provides its latest chips from two units of tessellation, we must remember that the GeForce GTX 580, there are 16 units of tessellation.