Apple 2019 Mac Pro: Not All Memory is the Same Speed, Mixing Sizes Not so Good
Memory bandwidth is especially important for more CPU cores and/or fast ones because it can constrain how quickly data can be accessed by each core. The 2019 Mac Pro in 16/24/28 CPU cores configurations needs all the bandwidth it can get.
With different memory configurations, how is memory bandwidth affected?
In the MPG review of the 2019 Mac Pro:
2019 Mac Pro: Memory Bandwidth