How Do Triple Memory Setups Work with Duo Channel CPUs?

Some of the notebooks out there have 3 ram slots, controlled by a duo channel CPU. When you fill all of them with equal/matched rams, how exactly does it work? Will it fall back to single channel?

 

The first pair of stick will be dual channel, the third will be single-channel. However, the performance difference between single- and dual-channel DDR3 RAM is so minimal that a lot of synthetic benchmarks have issues differentiating the two, let alone subjective difference.

 

Thanks for the reply.

So, if there are already 2 matched sticks running in duo channel, adding a 3rd will add space and won't bring any performance drop? Should I match the 3rd stick?

I know I'm bit paranoid here, but just to be sure, if 2 sticks are in duo and one in single, does the system kernel (Linux/*BSD) have any knowledge of the unevenness across physical address space? Will it try to use up the faster part first? Or there's some kind of striping involved to make it even?

 

It won't matter if you match the 3rd stick's capacity with the other two. You will still have two banks running in dual channel, and the third slot will run independently as a single channel module; no performance drop, more memory available.

Linux is very good with memory management, as is Windows, and the channel operation should not be affected. How the channels are utilized and in what order, I'm not entirely sure on though.