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Texture filtering

  Peak bilinear
filtering
(Gtexels/s)
Peak bilinear
FP16 filtering
(Gtexels/s)
Memory
bandwidth
(GB/s)
GeForce GTX 560 Ti (Asus) 53 53 128
GeForce GTX 570 (Asus) 45 45 152
Radeon HD 6870 (Asus) 51 26 134
Radeon HD 6950 (XFX) 73 37 166
Radeon HD 6970 (Asus) 85 43 176
Radeon HD 7850 55 28 154
Radeon HD 7870 GHz Edition 80 40 154

The results of this synthetic test track fairly closely with the theoretical peak numbers we calculated. We'd have expected the 7850 to perform a little better, though, all things considered.

Tessellation

  Peak
rasterization
rate
(Mtris/s)
Memory
bandwidth
(GB/s)
GeForce GTX 560 Ti (Asus) 1660 128
GeForce GTX 570 (Asus) 2968 152
Radeon HD 6870 (Asus) 915 134
Radeon HD 6950 (XFX) 1660 166
Radeon HD 6970 (Asus) 1780 176
Radeon HD 7850 1720 154
Radeon HD 7870 GHz Edition 2000 154

For what it's worth, the Radeon HD 7970's poor showing in TessMark back in December was due to a software glitch, as we subsequently pointed out in our 7950 review. The new Radeons fly here with AMD's latest drivers, handily outpacing not just their predecessors, but also their direct rivals from the Nvidia camp.

In fact, the 7870 outdoes the GeForce GTX 570 despite the GeForce's considerably higher peak theoretical rasterization rate. Why is that? We'd wager it has something to do with the underlying architecture behind those two cards. Pitcairn, just like Tahiti, has two geometry engines sitting entirely separate from the shader cluster. Nvidia's Fermi architecture, meanwhile, has a geometry engine in each of its shader multiprocessors (SMs). There are 16 SMs in the GF110 and 15 in the GTX 570. Our guess is that Nvidia's distributed approach incurs more synchronization overhead than AMD's architecture, which lumps fewer, more powerful geometry engines together on the GPU.

Shader performance

  Peak shader
arithmetic
(TFLOPS)
Memory
bandwidth
(GB/s)
GeForce GTX 560 Ti (Asus) 1.3 128
GeForce GTX 570 (Asus) 1.4 152
Radeon HD 6870 (Asus) 2.0 134
Radeon HD 6950 (XFX) 2.3 166
Radeon HD 6970 (Asus) 2.7 176
Radeon HD 7850 1.8 154
Radeon HD 7870 GHz Edition 2.6 154

And here, folks, is where the improved efficiency of AMD's Graphics Core Next architecture can be witnessed. Despite its slightly lower theoretical peak, the Radeon HD 7870 zooms well ahead of the less efficient Radeon HD 6970. The new Radeons make short work of the competing GeForces, too.

GPU computing

Ditto for this general-purpose computing test, where the GPUs put their shaders to work running a ray-tracing renderer written in OpenCL. Graphics Core Next is supposed to reap sizable benefits in general-purpose applications, and the evidence shows that it does.