SP (May 29, 2001 12:02 a.m.):
It has to do with the voodoo architecture. Since you have 2 chips of the card and one chip is rendering the odd lines and the other the even lines that means that when textures are stored both chips need to have a duplicate copy of the same textures stored in each of their half of the memory. So, in essence you have to have 2 redundant copies of the same texture data. That kinda cuts your texture memory in half. It was the same way with voodoo2. With 2 12MB voodoo2 cards in an SLI configuration each card had 4MB for frame buffer and 8MB for texture memory. However, the SLI configuration effective was the same as a 16MB card with 8MB of frame buffer and 8MB of texture memory. The reason being that the frame buffer memory was additive since each frame buffer contained a different half of the frame buffer data, but the texture memory on each card had to have an exact copy of the same 8MB of data. This was one of the shortcomings of the old outdated voodoo architechture that 3DFX continued to cling to. So, you see 64 MB of memory on a voodoo5 is only about the equivalent of 32MB on any other card.
If you want a real 64MB card you'll have to get something else like a radeon or geforce.