Does using more memory slots equal better bandwidth?

Question

I am thinking of buying a Mac Pro, and I am wondering about the various memory configurations. It can be had with 3x4GB, 4x4GB, 4x8GB or 4x16GB.

3x4GB seems like a weird configuration. I thought DDR memory had to come in pairs to use the memory bandwidth effectively. Is this correct?

And on that note, do you get a higher memory bandwidth with 4 slots occupied, than with 2 slots occupied?

Answer 1

It is possible for the memory to be faster if the hardware supports dual or quad channel memory. I don't know if Mac has this option or not. Many Windows and Linux computers with high end motherboards support this.