Help me understand memory

[zaxrex]

So I am already using ~6 of 8Gb RAM on my new work machine, and I'm not even really pushing it. So I was looking to upgrade.
My question is, why does the board support 32 Gb RAM at 1333 mhz but only 16 Gb at 1600 mhz? I can understand that the higher frequency means faster data transfer and that the board can only handle so much, but 4 1333 8Gb chips would seem to be able to push more data at any one time than 2 1600 8Gb chips. I'm probably missing something basic like geometric scaling means nothing in throughput, but I thought this forum may give me the answer I am looking for.

Oh, and one more question. Since I can mix 1333 and 1600 chips and they both are operated at the 1333 level, would putting in 4 1600 8Gb chips default to 1333 operation or only 16 would be recognized and used at 1600?

And if you say that the platform matters to the type of answer, it is a Dell M4600 i7 Vista Ultimate.

[Sabre]

Looks like the memory type/max is actually dictated by processor you have:Intel® Core™ i7-2760QM Processor

There is hardly any difference, speed wise, between the two types: Proof