Voodoo3 - Architecture and Performance

Architecture and Performance

Much was made of Voodoo3 (as Avenger was christened) and its 16-bit color rendering limitation. This was in fact quite complex, as Voodoo3 operated to full 32-bit precision (8 bits per channel, 16.7M colours) in its texture mappers and pixel pipeline as opposed to previous products from 3dfx and other vendors, which had only worked in 16-bit precision.

To save framebuffer space, the Voodoo3's rendering output was dithered to 16 bit. This offered better quality than running in pure 16-bit mode. However, a controversy arose over what happened next.

The Voodoo3's RAMDAC, which took the rendered frame from the framebuffer and generated the display image, performed a 2x2 box or 4x1 line filter on the dithered image to almost reconstruct the original 24-bit color render. 3dfx claimed this to be '22-bit' equivalent quality. As such, Voodoo3's framebuffer was not representative of the final output, and therefore, screenshots did not accurately portray Voodoo3's display quality which was actually much closer to the 24-bit outputs of NVIDIA's RIVA TNT2 and ATI's Rage 128.

The internal organisation of Avenger was not complex. Pre-setup notably featured a guardband clipper (eventually part of hardware transformation and lighting) but the pixel pipeline was a conventional single-issue, dual-texture design almost identical to that featured on Voodoo2, but capable of working on 32-bit image data as opposed to Voodoo2's pure 16-bit output. Avenger's other remarkable features included the 128-bit GDI accelerator first debuted in Banshee. This 2D engine led the Voodoo3 to be considered one of the more high-performance video cards of its generation.

The Voodoo3 2000, 3000 and 3500 differed mainly in clock frequencies (memory and core were synchronous). The clock rates were 143 MHz, 166 MHz and 183 MHz respectively. While this gave the 3000 and 3500 a notable theoretical advantage in multi-textured fillrate over its main rival, the 125 MHz TNT2,the TNT2 had nearly twice the single-textured fillrate of the Voodoo3. In addition, the Voodoo3 consisted of one multi-texturing pipeline, the TNT series consisted of twin single texturing pipelines. As a result, Voodoo3 was disadvantaged in games not using multiple texturing. The 2000 and 3000 boards generally differed in their support for TV output; the 3500 boards also carried a TV tuner and provided a wide range of video inputs and outputs.

At the time modern multi-texturing games such as Quake3 and Unreal Tournament were considered Voodoo3's performance territory, as Voodoo3's primary competition upon release was the dated RIVA TNT. NVIDIA's RIVA TNT2 arrived shortly thereafter and the two traded places frequently in benchmark results.

Although the Voodoo3 was a replacement for the Voodoo2, it was often beaten by Voodoo2 SLI cards in direct comparisons.

Voodoo3 remained performance competitive throughout its life, eventually being comprehensively outclassed by NVIDIA's GeForce 256 and ATI's Radeon. 3dfx created the ill-fated Voodoo 5 to counter.