CPU vs. GPU
Intel's latest quad-core CPU, the Core 2 Extreme QX6700, consists of 582 million transistors. That's a lot. But it pales in comparison to the 680 million transistors of nVidia's latest video card, the 8800 GTX. Here's a small chart of transistor counts for recent CPUs and GPUs:
AMD Athlon 64 X2CPU154 m Intel Core 2 DuoCPU291 m Intel Pentium D 900CPU376 m ATI X1950 XTXGPU384 m Intel Core 2 QuadCPU582 m NVIDIA G8800 GTXGPU680 m
ATI won't release a new video card until next year. But their current X1950 XTX isn't exactly chopped liver: 384 million transistors is more than any current dual-core CPU.
Of course, comparing GPUs to CPUs isn't an apples-to-apples comparison. The clock rates are lower, the architectures are radically different, and the problems they're trying to solve are almost completely unrelated. But GPUs now exceed the complexity of modern CPUs in terms of absolute transistor count. And like CPUs, they're becoming programmable-- it's possible to harness all that graphics power to do something other than graphics.
So far, the only types of programs that have effectively tapped GPU power-- other than the obvious applications and games requiring 3D rendering-- have also been video related: video decoders, encoders, video effect processors, and so forth. But there are many non-video tasks that are floating-point intensive, and these programs have been unable to harness the power of the GPU. Meanwhile, the academic world has designed and utilized custom-built floating-point research hardware for years. These devices are known as stream processors. Stream processors are extremely powerful floating-point processors able to process whole blocks of data at once, whereas CPUs carry out only a handful of numerical operations at a time. We've seen CPUs implement some stream processing with instruction sets like SSE and 3DNow!, but these efforts pale in comparison to what custom hardware has been able to do. 3D rendering is also a streaming task. Modern GPUs have evolved into stream processors, sharing much in common with the customized hardware of researchers. GPU designers have cut corners where they don't need certain functionality for 3D rendering, but they have ultimately developed extremely fast and flexible stream processors. Modern GPUs are just as fast as custom hardware, but due to economies of scale are many, many times cheaper than custom hardware.
