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Pixel fill and texturing performance

Peak pixel
fill rate
(Gpixels/s)
Peak bilinear
integer texel
filtering rate
(Gtexels/s)
Peak bilinear
FP16 texel
filtering rate
(Gtexels/s)
Peak
memory
bandwidth
(GB/s)
GeForce GTX 460 768MB 16.8 39.2 39.2 88.3
GeForce GTX 460 1GB 810MHz 25.9 47.6 47.6 124.8
GeForce GTX 470 GC 25.0 35.0 17.5 133.9
GeForce GTX 480 33.6 42.0 21.0 177.4
GeForce GTX 570 29.3 43.9 43.9 152.0
GeForce GTX 580 37.1 49.4 49.4 192.0
Radeon HD 6850 25.3 37.9 19.0 128.0
Radeon HD 6870 28.8 50.4 25.2 134.4
Radeon HD 5870 27.2 68.0 34.0 153.6
Radeon HD 6950 25.6 70.4 35.2 160.0
Radeon HD 6970 28.2 84.5 42.2 176.0
Radeon HD 5970 46.4 116.0 58.0 256.0

The theoretical peak numbers in the table above will serve as a bit of a guide to what comes next. Different GPU architectures achieve more or less of their peak rates in real-world use, depending on many factors, but these numbers give us a sense of how the various video cards compare.

Versus its most direct rival, the GeForce GTX 570, the Radeon HD 6970 has comparable rates all around. Although the GTX 570 has a wider 320-bit memory interface, the 6970's amazing GDDR5 clock speeds more than make up the deficit. The fact that the GTX 570 can filter FP16 textures at its full rate, rather than half, is no obstacle for the 6970, either, since Cayman's higher unit count and clock frequency allows it to reach similar FP16 filtering rates, at least in theory.

The closest "competitor" to the Radeon HD 6950 is last year's model, the Radeon HD 5870. The 6950 is only a little faster than the 5870 across the board—and that's the stock model. We've also tested a slightly overclocked version of the 5870 with 2GB of RAM, which should provide us with an interesting and very direct comparison between the Cayman and Cypress architectures in which key rates are nearly equal and efficiency becomes the question.

This color fill rate test tends to be limited primarily by memory bandwidth rather than by ROP rates. True to form, the 6970 and 6950 outperform the GeForce GTX 570 here.

Notice, also, that I've tested a trio of older cards for historical interest, including the Radeon HD 4870, the GeForce GTX 280, and the oldest DX10 chip on the planet, the GeForce 8800 GTX. They can only participate in a subset of our test since they're not DX11-capable, but they should be fun to watch and compare.

3DMark's texture fill test doesn't involve any sort of texture filtering. That's unfortunate, since texture filtering rates are almost certainly more important than sampling rates in the grand scheme of things. Still, this is a decent test of FP16 texture sampling rates, so we'll use it to consider that aspect of GPU performance. Texture storage is, after all, essentially the way GPUs access memory, and unfiltered access speeds will matter to routines that store data and retrieve it without filtering.

AMD's raw sampling rates were already quite a bit faster than Nvidia's, and Cayman's higher unit count puts some additional distance between the two.

Cayman's much higher theoretical texture filtering rates work out to somewhat higher measured throughput in RightMark, but nothing like the 2X advantage the 6970 has over the GTX 570 on paper. Then, in our FP16 filtering test, the 6970 doesn't deliver on nearly as much of its promise as the GTX 570 does—and the GTX 580 is faster still.