TNT is Dy-No-Mite! The 3D Accelerator Demystified
Buying a video card used to be a fairly simple process. All that you had to do was find out which manufacturer produced a card with the feature-set you required and the decision was pretty much made. Today, with the 3D accelerator market booming, the card manufacturer is almost irrelevant and the chipset (the basic instructions that the card uses to put images on your screen) that is used is what determines the speed and features that the video card has. The decision of which card to buy is further complicated by the issue of whether you want a single 2D/3D card or separate card to handle 2D and 3D graphics. The combo card will cost less but, at least until recently, having two separate cards resulted in greater performance.
Last summer, the 3Dfx Voodoo2 chipset was the fastest of the fast. This 3D only chipset requires the use of a second video card to handle 2D graphics, like those in Windows for example. The 3D card then prevents the 2D card from processing 3D information and does it itself much faster. The Voodoo2's image quality is very good, however, the cards tend to produce colours that are a little washed out and images are a bit fuzzy, as if they are slightly out of focus. The ability to play Quake2 at 60 frames per second (fps) compensates for these minor complaints. For the absolute fastest 3D performance, the Voodoo2 allows you to put a second card Voodoo2 card in your computer in ScanLine Interleave mode (SLI). Each card then processes the images of every second line essentially doubling the speed at which images are displayed. Even today, the Voodoo2 in SLI mode remains the absolute fastest 3D solution for gaming.
Toward the end of the summer, nVidia released its TwiN-Texel or TNT chipset. Cards made with this chipset have all the latest features like single-pass multitexturing, bi- and tri-linear filtering, 32-bit rendering, etc. There isn't space in this article to explain what all of these fancy terms mean, suffice it to say that they're all good. Excellent definitions and explanations of these terms and more can be found on the AnandTech web site in their article call Image Quality Explained at http://www.anandtech.com/html/review_display.cfm?document=323.
The Velocity 4400 by STB is a TNT based card that rivals the performance of a single Voodoo2 card and has excellent image quality with bold, rich colours and fantastic detail. I tested both the AGP and PCI versions of the Velocity, each with 16 MB of RAM, and found both of them to be excellent for both gaming and general use. The 2D performance is very good, but at very high resolutions (at 1280*1024 or above), the images become blurry. These cards may not be adequate for anyone with a 19 or 21 inch monitor that runs at these resolutions. If this applies to you, perhaps a Matrox G200 card would be more appropriate. The Velocity 4400 also has TV output up to a resolution of 800*600. The implementation is good, but not great and images are slightly blurrier than some of the better ones I've seen. It's fun to play games on a display the size of a television, rather than a monitor, as a novelty, but not for day to day usage.
Now, on to what's really important. 3D performance is first rate. I ran several benchmarks on a Pentium2 (P2) running at 300 MHz with 128 MB RAM to measure the performance of the Velocity 4400. Quake 2 was played at a resolution of 800*600 and 16-bit colour depth. The AGP card displayed 48 fps and the PCI card scored 37 fps. This discrepancy is due to the larger bandwidth of the AGP bus. Generally, the performance difference between the AGP and PCI versions isn't quite this large. My single 12 MB Diamond Monster 3D 2 (Voodoo2 chipset) scored 52 fps, just barely outpacing the STB card. During actual game play, there is no noticeable difference in performance, however with the STB, the images tended to be fairly dark even with the brightness turned all the way up. When the same test is run on an overclocked 450 MHz P2 Celeron, the TNT bests the Voodoo2 by a few frames per second (remember overclocking is dangerous and can fry a system – proceed at own risk). The maximum resolution that a single Voodoo2 can draw is 800*600, but the TNT can go higher for better image quality. Framerates remain high enough to be playable at 1024*768. Some people, myself included, don't mind dropping a few frames per second to play at a slightly higher resolution, while other speed demons prefer lower resolutions and higher framerates for smoother play. For verification, I ran other benchmarks but found similar results.
Another feature the TNT supports that the Voodoo2 doesn't is 32-bit rendering. When images are rendered at true 32-bit colour, dithering effects that tend to crop up are minimised, resulting in a better quality output. However, since literally twice the amount of information has to be processed, framerates drop substantially. I'd recommend keeping with 16-bit rendering until the next generation of super-fast 3D accelerators starts to appear.
The Velocity 4400's biggest problem is that of heat. Even after a short time, the card, especially the PCI version, becomes hot to the touch. The Velocity 4400 comes with a small heat sink on the TNT chip, but a fan would be better. For the do-it-yourselfers out there, a 486 fan mounted on top of the heat sink will result in a substantially cooler card.
The bottom line is that for much less than the cost of separate 2D and 3D video cards, top notch performance can be had using a single TNT based card. I'd recommend the PCI version for older Pentium systems and the AGP version for newer P2 based computers. Buying a 3D accelerator is always tricky because something newer and faster is always right around the corner, but for today, TNT is where it's at.
by Jason Offiong
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