3DMark2003 Fill rate
tests measure the fill rate speed of drawing textures onto 3D
objects of the graphics card. Single-Texturing test draws one
texture into 64 surfaces which means the graphics card fills
each of these objects separately, no matter how many texture
layers that card is capable of drawing in a single pass. GeForce
FX 5900 Ultra is clearly fastest here and interestingly FX 5600
Ultra is faster than the FX 5800.

Multi-Texturing test
which draw 64 texture layers in the shortest possible time will
allow the cards to perform close to their theoretical peak.
GeForce FX 5800 Ultra and FX 5900 Ultra are able to generate two
textures units per pixel pipeline while GeForce FX 5600 Ultra
can only draw a texture unit per pixel pipeline. This could lead
to considerable performance limitation for GeForce FX 5600