The Millenium G400 is, by Matrox's own admittance, a "dramatically different" 3D chip. Mainly because this time, it could actually do 3D in an acceptable manner. Slow, but acceptable.

Tech Sheet - Parhelia

RAMDAC 300 Mhz
Transistor count (millions)
Technology 0.25 micron
Frequency 125 Mhz
Onboard RAM 16/32 MB
Memory bandwidth GB/s
RAM bus width 128 bits
RAM bus frequency 166 Mhz
Pixel fill rate MPixels
Texel fill rate 250 MTexels
Triangle count (millions)
Render pipes
Pixel per Clock (per pipe)
Z-buffer 32 bit

The Matrox Millenium The Millenium G450