However, I can't help but think that it's almost pointless to have a high multiplier. The only thing it helps with is calculations that can be stored in the CPUs cache, no?
It's far from pointless to have a higher multiplier. Current (super scalar, pipelined, out of order) CPUs could not possibly process all the data they would beable to recive a 1:1 (cpu:bus) memory and/or system bus, in the vast majority of situations. If you double a modern CPU's data buses and halve the multiplier, you will probably see a nice performance increase. Howerver, if you go further and tripple it while cutting multiplier three fold you would see much less of a boost. Efficency drops at each stage. You will eventually hit a wall where the CPU just cannot process data anyfaster, so will stop asking for it till it needs more.
This is why, with my new S939 dual channel setup, I get only about 50-60% more memory bandwidth than I did with the same memory and settings in a single channel config. Max theoretical bandwidth did double, but my CPU is not fast enough to process all the information it recieves in many cases. I am not normally limited by memory bandwidth even with a CPU clock 12 times as fast as the memory clock. I actually have more *usable* memory bandwidth running the memory at 194MHz with the CPU at 2.71GHZ than I do with the memory running at 250MHz and the CPU running at 1.5GHz, for example.
CPUs do alot of stuff with a given instruction and peice of data. They do not need massive relative bandwidth to reach their limits. It takes alot longer than 1 clock cycle to process most anything.
When I raised my multiplier, my arithmatic benchmarks did major jumps but things like 3Dmark only had a few extra marks. hm.
3dmark tends to be video card limited.
This is where the term bottleneck comes in. If one component is faster at getting a given task done than other components, you have a bottleneck. It's going to vary from program to program and task to task. When recording video my hardrive is the bottleneck. When encoding video, my CPU is the bottleneck. When playing BF2, my video card is the bottleneck.