Pushing the Frame
Rate Envelope
Last month, ATI finally launched their Radeon X1900
series, formerly known as R580. From a feature stand point,
it's not that much different from their very late-to-market
Radeon X1800 series. However, there is one very distinctive
difference between the two - the number of pixel shader
units. Whereas the Radeon X1800 has 16, the Radeon X1900
comes equipped with 48 shader units. The reason: to push
shaders as fast as possible.ATI's reasons for going bonanza with shaders is not without reason or deep thought. Newer games rely more and more on shaders instead of textures. But that's not the only reason. Textures not only take up space but is very heavy on bandwidth as well. The burden can even be too much for the current generation of graphics cards, even high end monsters like the GeForce 7800GTX or Radeon X1900 XT. GDDR3 memory clocks is already near its upper limits and that also apply to memory controllers in use by these cards as well. Next year's games or even this year's will soon come, with more detail, be it with textures or shaders (or a mixture of both).
Beyond3D recently had an interview with Eric Demers concerning ATI's design decision with the Radeon X1900 (which you can read here). It certainly raises some interesting questions and facts, which could be useful to predict where we will be going to in the next year or so. In particular interest to us, is of course the decision to go with more pixel shader units and maintain the number of ROP units. On the other hand, NVIDIA seem poised to extend the G70 - the GeForce 7 series - architecture further by adding more G70-like quad.
So, we decided to play around with a GeForce 7800GTX some more. This time, we took it for a spin to see the influence of quads, core and memory clocks on current games. This article started out as something to do on the weekend, but it quickly become more and more interesting (at least to us) as testing progresses.
Getting Ready
From the current crop of games, there are two games which we feel correspond to the texture dependent vs shader heavy games perfectly: Quake 4 and F.E.A.R. Despite having lower hardware requirements, F.E.A.R is definitely heavier of the two. Quake 4 on the other hand is still (loosely) based on the Doom 3 engine, which in turn still uses shaders from the pre SM 3.0 era. Both games looked amazing when viewed in full detail and gamers and reviewers alike used both extensively for making graphics card purchase decisions.There's also something else both games share. Even with a GeForce 7800GTX or a Radeon X1800XT, you won't get high enough playable frame rates with AA and AF above 1024 x 768. Now that's heavy. The only way to get faster frame rates short of overclocking the card is by using multi rendering solution from both ATI and NVIDIA, Crossfire and SLI, respectively. But as we pointed out in our last article, this is not always the best solution.
Now that we have the games, we must choose how to enable / disable quads inside our sample of GeForce 7800GTX and change its core and memory clock. Since we don't want to do any hard modding (it is still a sample after all), we decided to rely on Alexey Nikolaychuk a.k.a Unwinder utility, RivaTuner. Some might ask why not just use the GeForce 7800GT and newly released GeForce 7800GS. Well, this is not meant to be a review of those cards. We wanted to see what kind of influence one or two quads have on performance, both on different and similar clocks.
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