Originally Posted by zash
Intel 965/975 based motherboards have 10GB/s with DDR2-667 and 12GB/s with DDR2-800 memory. Mac Pro (intel 5000 chipset) have up to 20GB/s bandwith with FB-DIMMs (need to have 4 FB-DIMMs), or half that with 2 FB-DIMMs. FB-DIMMs have more latency (especially when using 4) than DDR2, but you get more bandwith and higher capacities...
Also, Intel is going to release Quad-Core cpu's by the end of the year, which may or may not work in current Mac Pro's, which would give you a total of 8 cores.
Do any of these differences affect latency in audio? I doubt it will much. Software (Drivers, OS and apps) will have much more effect on real world latency. Having more bandwith won't hurt, but if you look at the cost of a Xeon setup vs. A Core 2 setup, it's not really worth to spend the extra money for latency reasons (unless you don't care much about the cost).
Very interesting , thank you for the reply.