Shader processing — continued

So how powerful is the GT200's shader array? With 240 cores operating at 1296MHz, it's potentially quite formidable. The table on the right should put things into context.

As you'd expect, the GT200's peak computational rate will depend on whether and how much it's able to use its dual-issue capability to get that third FLOP per clock. We can probably expect that the GT200 will reach closer to its dual-issue peak than the G80 does to its own, but I suspect the GT200's practical peak for graphics processing may be something less than 933 GFLOPS.

Nevertheless, the GeForce GTX 280 looks to be substantially more powerful than any other single-GPU solution, and it's not far from the two dual-GPU cards we've listed, the Radeon HD 3870 X2 and the GeForce 9800 GX2. I should point out, however, that the GTX 280 just missed being able to claim a teraflop. Surely Nvidia intended to reach that mark and somehow fell just short. I believe we'll see a GT200-based Tesla product with slightly higher shader clocks, so it can make that claim.

The GT200's shader tweaks pay some nice dividends in 3DMark's synthetic shader tests, as the GeForce GTX 280 grabs the top spot in each. The parallax occlusion mapping test is where the GT200's larger register file is reputedly a big help, and both GeForce GTX cards top even the 9800 GX2 there, despite the fact that performance in that test scales well on the multi-GPU cards.

Neither multi-GPU solution scales well in the GPU cloth and particles benchmarks, however, and those cards are left to fend for themselves on the strength of a single GPU. Surprisingly, among the single-GPU options, the GT200 is only incrementally faster than the GeForce 8800 GTX and 9800 GTX in both tests.

The Radeons mount more of a challenge to the GeForces in the Perlin noise benchmark, but once again, the GTX 280 captures the top spot, and the hobbled GT200 in the GTX 260 nearly matches a pair of G92s on the 9800 GX2. Both the larger register file and the improved dual-issue on the GT200 are purported to help out in this test, and those claims are looking pretty plausible.