Why AMD depends on RAM

I have a question that two of my friends just had their own PC setups built with almost the same specs just that the RAM used was DDR3 for one and DDR4 for the other but had the same AMD processors in it. I searched around and some sites said that AMD processors depend on RAM speed. Now why is that.?

I think a lot of the time AMD CPUs can be a bit more fussy about the type of RAM used with them. It’s always good to get the RAM marked as AMD compatible to avoid any issues.