gaara said:PS3 is a DirectX 9c instruction, previous versions of DX(aka b) do not support this instruction, and thus, if your card does not support PS3, it will revert to DirectX9b, not DX8 or whatever other myth.
It will only revert to DirectX9b if the games have DX9b instruction. Recently, games have only been comming out with DX8 and DX9c instructions, and have not included DX9b, so it DOES revert to DX8 if SM3 is not found.