Compute max memory bandwidth of a processor

Question

I'm reading this CPU specification: http://ark.intel.com/products/67356/Intel-Core-i7-3612QM-Processor-6M-Cache-up-to-3_10-GHz-rPGA

It says the CPU has 2 channels. So I think it has 2 memory controller inside. Then the max memory bandwidth should be 1.6GHz * 64bits * 2 * 2 = 51.2 GB/s if the supported DDR3 RAM are 1600MHz. But the specification says its max memory bandwidth is 25.6 GB/s. I multiplied two 2s here, one for the Double Data Rate, another for the memory channel.

Is it the problem of the specification? or I have some miss understanding?

Loleta

Why do you have two factors of 2 there ? One for DDR and one for the presumed two memory controllers ? – Hydrops

Yes. one for the Double Data Rate, another for the memory channel number. – Loleta

Answer 1

Double data rate memory specs usually already take into account that its effective frequency is doubled. "1600 MHz memory" really runs on 800 Mhz, so you can leave out one factor of 2 from your calculation.

Dismiss