Once this was the top of the line graphics card from 3dfx! The 3dfx Voodoo5 5500 AGP with 64MB SDR-SDRAM and two VSA-100 chips. Each chip has access to 32MB so the effective usage of RAM is about 32MB, not 64MB 
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The VSA-100 chip features Anti-Aliasing (often abbreviated with AA) and because the Voodoo5 has two chips it was quite a good solution for AA back in the old days. AA is used to remove the 'jaggies' or otherwise said: ugly pixels on edges of objects.
The Voodoo5 5500 is the perfect example of how SLI on an AGP card should work. ATi had the Rage 128 Pro MAXX edition but the card only works in single-chip modus on Windows 2000 and XP systems due to a design error. The VolariDUO V8 Ultra had a way to narrow 'BitFluent' bus between the two chips. It only featured 2,1GB/s which is probably too small. It was not until PCI-Express came before good SLI implementations arrived. The AGP bus was actually not suitable for dual chip design as it could only address one chip. This means there has to be a master chip and a slave chip: that's where bottlenecks are created.
As benchmarks turn out the SLI implementation on the Voodoo5 makes the two VSA-100 chips move in to the fast lane!
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