Is it possible to saturate the memory bus using high frequency DDR4 memory, even if a motherboard claims support for it?

Question

So a friend of mine asked for some DDR4 memory recommendations since he was still using DDR3 and wanted to buy a new motherboard, preferably B450 chipset so he could buy a Ryzen. I told him to buy a set of 3000MHz Crucial Ballistix RAM, being Micron E-Die and all it would overclock pretty good - I've seen very good results even in an A320 board.

But then some guy came in and said no one would ever need memory faster than 2666MHz (ridiculous, right?), and that high bandwidth RAM - like 3000/3200MHz - would saturate the memory bus. He backed this up by saying he had a degree in Computer Engineering, but I still doubted his claims.

This was some time ago, but it still has me thinking about it. What made him start talking about memory "bus" when no one else ever mentions it when talking about, or recommending, DDR4 RAM? Is it actually possible, to ""saturate the memory bus bandwidth"" (whatever this means), with just 3200MHz memory? Wouldn't this require some tinkering with threads with a low-level programming language like C?

Answer 1

Yes, it is a legit term: See this Intel paper. However, for consumer use, sounds like mulefeathers to me.

Motherboard logic dictates whether DDR3 or DDR4 can be used, and a quick look at some B450 boards shows many of them supporting faster than 3200MHz DDR4 RAM.