I fully agree with Dave. There's an enormous difference between the feature set / architecture of console chips resembling SM3-capable PC GPUs and actually being SM3-capable PC GPUs (and that's before you consider the huge differences in the overall platforms). My expectation is that SM3 probably won't receive a huge amount of attention from engine builders. I think one further aspect that hasn't been mentioned goes something like this: If you add up all the R3xx, R4xx and NV4x chips you get a whole bunch of GPUs that provide reliable SM2 performance. However, do the NV4x chips qualify as "reliably fast" SM3 products? If you observe the rather painful hit that NV40 takes running HDR lighting effects you might conclude they do not. Or look at it another way - in many respects Doom 3 is the ultimate DX8/sm1 engine (ok, it's much more complicated than that since its openGL not DX and since its leverages some NV-only shadow rendering technilogy). And that didnt appear until well into the life cycle of DX9 hardware. In fact, there were very few games put out that heavily leveraged the features available in DX8/sm1 before DX9/sm2 came along. Perhaps the industry goes incycles, missing out alternate shader models. In that scenario we go from DX7 and no shaders, we largely skip dx8 / sm1 support, see widespread coding for sm2, once again we largely skip sm3 and see widespread support for sm4. That's an over simplification and that's notreally how I see it, but I think there's an element of truth in there.
