Quote Originally Posted by narciso View Post
I would like to see how much scaling memory speed translate to haswell performance. I have seen some tests here in phoronix but they only tested to 1600mhz, and it shows performance scaling.
Regarding dual rate ram, most ram now are dual rated (double sided ram).
Thats not what it means. The sticks themselves aren't dual channel, they are independent of that. the memory controller is what dictates how many memory channels are available. Most chipsets for the last decade have been dual channel, where if you have 2 sticks of ram with the same capacity, CAS and speed installed in the proper slots the controller will split up the data being split up and sent to the individual channels for increased bandwidth.

It's the same thing you see with GPUs and their bit rate, the increased bitrates are more channels being added to the GPU's memory controller. On low end GPUs you'll see various memory setups on the same chip, these are because the manufacturers are allowed allot of leniency in what they use, most of them support 128-bit GDDR1-2-3-5 but can be found in a setup as low as 32 bit, which is caused by the manufacturer only installing higher capacity memory chips on one channel to cut costs.

Now that said, AMD had previously stated that increasing the number of memory channels on a CPU only system results in increased latency and generally ends up as a wash performance wise. With a GPU in the mix I've got no idea if quad channel system ram would be of help for the APU as the increased bandwidth may help the GPU side but hurt the CPU side on latency.