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Old 12-17-08, 10:23 PM   #33
ChrisRay
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Join Date: Mar 2003
Location: Tulsa
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Default Re: Nvidia's GTX 295 pics.

Except. Memory bandwith doesnt scale well with the GTX 280. You can add loads of bandwith and get nearly nothing. If the card was extremely bandwith limited. Scaling Core/ROP domains would not increase performance the way it does. Yet it does. Pixel and texture fillrate bottlenecks simply arent constrained by bandwith on the GTX 280 ((or 260 for that matter)).


Do some experiments yourself with Anti aliasing ((the most heavily zfill/bandwith limited tests there)). And watch as you gain more per clock than you do per bandwith. You reach a certain point where bandwith becomes a limiting factor on the texel and pixel fillrates. But currently these bandwith limitations are not that reachable. Since core clocks continue to be the best scaler of performance.

Next experiment with a low end card with little bandwith but high core clocks. You will get the exact opposite performance gains by increasing the bandwith verses the core clocks. Bandwith is only extremely useful if you have the fillrate to make it happen. As I said. Most of the GTX 280's bandwith is wasted. The improvements come with increased pixel/zfill fillrate than actual bandwith. This is why its so easy for GTX 260 cards to hang with GTX 280 cards with some core clock adjustments despite the bandwith disadvantage.

Chris
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