While I agree with most of what you said, not everything is the same between models, even if it looks like it on paper. The quality of the chips used between models can vary greatly, no different than the way in which some processors have very different characteristics based on how they are binned. The FX-8370 and 8320, for example, use the exact same chip, but one is a higher quality chip than the other and is hand picked for that reason to represent a higher capability unit. Two otherwise identical memory modules, that use different chips, may have much different capability when it comes to timings, voltage or speed potential.