According to an rumor posted on Xbit Labs, nVidia’s G80 will not have unified shaders contrary to previous claims. In the current generation of video cards, a fairly sharp distinction is made between pixel and vertex shaders, both on the hardware side and on the software side. However, with the arrival of DirectX 10, one instruction set is defined that works for both pixels and geometry, so that separation disappears at least on the software side. Although it is not mandatory to merge it in this way within the hardware (into so-called ‘unified shaders’), it seemed like a logical move in terms of efficiency. For example, the next generation of ATi is expected to use unified shaders, partly because the company has already designed such a GPU for the Xbox 360.
However, according to nVidia, there is still enough stretch in their current architecture. Previously, the company stated that unified shaders will not be used until and when it is deemed useful. Until then, DirectX 10 may therefore be supported with separate pixel and vertex hardware. The consequences of this for performance are, however, unclear. The new video cards from ATi and nVidia are expected around the same time as Windows Vista, so by the end of the year. In the meantime, nVidia will release the 90nm G71 core, a speed boost for the GeForce 7800.