3dfx Velocity 100

by Mike Andrawes on October 29, 1999 7:50 PM EST

Exploring the Velocity

Once the Velocity arrived in the AnandTech labs, we were able to probe more carefully into its abilities and features. Although Voodoo3 drivers did not recognize it as a Voodoo3, although Powerstrip did detect it as such. Upon closer inspection, the drivers on the CD all use the same filenames as the "real" Voodoo3, but contain strings specifying their use for Velocity cards. We explored further still and found that as long as the .inf file from the Velocity was used, we could get Voodoo3 drivers to work on the Velocity. So far, it sounds a lot like the Velocity is a Voodoo3 in disguise. As noted above, the latest version of Powerstrip detected the Velocity as a Voodoo3. The clock speed was reported as 143 MHz, just like the Voodoo3 2000.

The first sign that something was up came in Quake 3, where the driver info tab identified the card as a Voodoo Banshee with 1 TMU (Texture Mapping Unit). But the spec sheets claim single pass multitexturing as a feature of the Velocity. Further, while Quake 3 scores suggested that just 1 TMU was in use, Expendable scores were equal to or even higher than a Voodoo3 2000 in some cases. We’ve seen in the past that Expendable is definitely capable of taking advantage of multitexturing, so we cannot attribute this to the Velocity only having 1 TMU.

We wrote 3dfx inquiring about what was going on here. They let us know that the Velocity does in fact have 2 TMU’s, just like the Voodoo3, but that it is disabled in OpenGL/Glide for "memory management purposes."

Floating around the web and the newsgroups is a registry key that can enable the second TMU. If you’re comfortable editing the registry, simply go under

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Display\0000\Glide

And add the value

FX_GLIDE_NUM_TMU

And set it equal to 2.

Perhaps it was disabled for memory management purposes, but AnandTech observed no ill effects with it enabled – just a healthy performance increase in OpenGL and Glide apps, bringing it right up to par with the Voodoo3 2000.

So for all intents and purposes, the Velocity does use a Voodoo3 chipset combined with slightly modified drivers that disable one TMU under OpenGL and Glide. The only real disadvantage to the Velocity is that the memory is cut from 16MB on the "real" Voodoo3 down to 8MB on the Velocity.

Specifications The Card and Drivers

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