NVIDIA GeForce 7800 GTX Review
Radeon X850 XT PE
GeForce 6800 Ultra
|Peak Pixel Fill|
Per Pixel Pipeline
NVIDIA claims that GeForce 7800GTX is a completely new GPU
architecture and is the most complex GPU ever built. It contains a whopping 302M
transistors manufacture on a more mature 0.11 micron process at TSMC. The die
size of 7800GTX is still slightly larger than the 6800U although it is based on
0.11 micron compared to 0.13 for the 6800U since it packs 80M more transistors.
It has 24 pixel pipelines and 8 vertex shader units compared to 16 and 6
respectively in GeForce 6800Ultra. The core of GeForce 7800GTX is clocked at a
430Mhz, just some 5Mhz more than its the 6800 Ultra and the memory is at 1.2Ghz,
some 100Mhz higher than 6800 Ultra.
If you look at the diagram above, the G70 macro architecture
isn’t too different from the NV45 architecture but NVIDIA claims that it is
designed from ground up. However, NVIDIA has made many micro architectural
changes to the pixel, vertex and texture engines; more pixel shaders, more
vertex shader and more efficient shaders. NVIDIA has also improved the
efficiency of the Cull / Clip / Setup on the G70 compared to the NV40 improved
by over 30% in fixed-function portion of the vertex pipeline. Also it is
interesting to know that G70 share close similarities to the RSX graphics
processor of the Sony Playstation 3.