Some benchmarks aren't fill-rate limited OR Geometry limited on certain video cards (read 3Dfx cards). How is it then, that these cards can pump out under 25fps in a game where an inferior (AGP) card can do 40+ with ease? If you ever see the Voodoo2 getting absolutely throttled by "lesser" cards (G200, i740, etc.) You can almost be sure that it has something to do with bandwidth.
Some Bandwidth Limited Benchmarks
The only true bandwidth limited benchmark that I have seen is the S3 mon2.dm2 benchmark. This benchmark uses over 20MB of textures in the scenes, bringing any non-AGP card (with under 20 MB texture memory) to its knees. Even though mon2.dm2 is the only benchmark out there which really needs AGP to run; more and more game manufacturers are coming out with games which require a lot of texture memory. (Epic had to do serious texture management "things" to get Unreal to run acceptably on the Voodoo2, a PCI card) You can expect future games to use well over 8 MB of texture in a single scene. Anything more than this, and that Voodoo2 starts to slow down big time...
Recognizing a Bandwidth Limited Benchmark
The ideal Case
Since Bandwidth is not related to either Fill-rate or CPU Speed, the FPS vs CPU Speed graph of a Bandwidth limited benchmark will yield a horizontal line..
The real world situation
The real world situation won't change much. Possibly a 3fps fluctuation between a PII/233 and a PII/400 due to decreased latencies with faster CPU, higher bus speed, etc.
Bandwidth limited benchmarks are scarce, and very easily recognizable. Read on to find out about Combo limited benchmarks...