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Lowdown on the Voodoo
5
Okay, I know that everyone, including myself has been anxiously
awaiting the debut of 3dfx's Voodoo 4 and 5 series on the
shelves of retail stores. While this hasn't happened yet, and probably
won't until late May of this year, I have managed to scrape together
some details on 3dfx's new-generation products. Unfortunately, we have
been unable to secure a Voodoo 5 for ourselves, so you will have to
forego the benchmarks.
Overview
As has been known for some time, 3dfx;s
new product line will include four variants, the Voodoo 4 4500, the
Voodoo 5 5000, the Voodoo 5 5500, and the top of the line Voodoo 5 6000,
based on the VSA-100 chipset. The Voodoo 4 4500 will be the low end
model, with comparable performance to the Voodoo 3, except with 32bit
color, and 32MB of SDRAM. The next step up the performance ladder will
be the Voodoo 5 5000, which is somewhat an anomaly, as it will only be
available in a PCI version. This card will support two VSA-100
processors, but only 32MB of memory. The third card, which will probably
be the most interesting to prospective buyers is the Voodoo 5 5500. This
card will run with two VSA-100 chips, and 64MB of RAM, divided into two
32MB banks. An interesting feature of this card is that it will require
to be plugged into a spare four-pin power cable inside the pc, to
alleviate any possible power problems from the AGP slot. The last behemoth
in this lineup, the Voodoo 5 6000, will sport four
VSA-100's and 128MB of the standard SDRAM. This monster, to be
released later this year, will have twice the power of the Voodoo 5
5500. In fact, it's power needs will be so great that a wall power
adapter will be included, to plug into a connector in the back plate of
the card.
The VSA-100
The VSA-100 is 3dfx's new
scaleable-architecture 3D chip, that serves as the base for the Voodoo 4
and 5 product lines. One VSA-100 is not at all spectacular by itself,
and is easily out-performed by any GeForce. In fact, the performance is
similar to the last generation Voodoo 3, albeit with 32bit color and
provision for more memory. This chipset only truly shines when incorporated
into dual or quad arrays, which effectively double or
quadruple its performance. So far, the VSA-100 has only been tested at
166mhz, with a synchronous memory clock, but production speeds are
expected to be marginally higher. If 3dfx's claims are true, the final
clock speed will probably be between 166 and 183mhz, as this number
coincides with the projected fill rate of 333 to 367 megapixels per
second. In quad or dual arrays, this would of course be increased to
1.33 to 1.47 gigapixels, or 666 to 724 megapixels.
T-Buffer Anti-Aliasing
Of all the hype that surrounds the
Voodoo 5's, the most publicized is the new two and four sample anti-aliasing,
via the T-Buffer. In simple terms, anti-aliasing is the process either
carried out by the hardware or software to remove visual anomalies from
the picture displayed on screen. These anomalies include the dreaded 'jaggies',
when lines appear to be rough around the edges, abrupt and unrealistic
transitions between textures, and shimmering pixels at a distance.
Although anti-aliasing improves the picture quality, it causes a large
performance hit. Most other videocard companies use the
down-sampling method to achieve anti-aliasing, but 3dfx, believing they
had a better method, chose to steer their own course. The down-sampling
method involves rendering a scene at a higher resolution than it will be
displayed at, usually 1600 x 1200, and shrinking it to the proper
dimensions. When the hardware encounters pixels that were present in the
high-res scene but not the low-res one, they are, so to speak, grayed
out, to blend smoothly from one object to another. While this method
works, it has the disadvantage of not being implemented in Glide
or Direct3D games. On the other hand, 3dfx's solution will work on any
3D-accelerated game ever made. Now when you think about it, that is a
large library of titles. This compatibility is achieved by performing
the anti-aliasing entirely in hardware, thus making compatibility
problems redundant. The way this works is by making the card process the
3D scene twice, or four times for the four-sampling method, and
averaging the pixel results together, as if it were a math problem.
Although this system works quite well, it is a serious drain on the
processing power of the card, because it divides that power by two or
four. As I mentioned before, this feature can be applied to any 3D
accelerated game, via 3dfx's control panel, which allows the user to
turn anti-aliasing effects on and off for any particular title. A final
note: four-sample anti-aliasing is not enabled for the Voodoo 4, as it
would pose to serious of a drain on the card.
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