Bus/Memory speed doesn't matter for the most part. It won't really ever bottleneck you unless your CPU/Mobo are complete trash. But a calculation you can do to work it out is dividing the processor's speed by the number of cores, e.g. the AMD FX-8320 runs at 3200mHz and has 8 cores, so 3200/8=400mHz. Dont worry about it though.