must memory modules be 100% identical for dual channel?

I bought an HP Pavillion g6-2210us notebook PC about 6 weeks ago; the OS is Windows 8. It has 4 GB of RAM (1 - 4GB module) and I'm thinking about adding another 4GB in the second slot. By using CPU-Z, I learned that the original module is a Kingston model. If I do a search on the model # shown by CPU-Z, I find nothing. I found what Kingston shows on their website for my computer but I don't what slight differences there may be between my current module and the two options found on Kingston.com.

I know dual channel basically requires two modules of the same size and speed. And, obviously, buying two of the same module at the same time is the surest way to achieve the objective. But, I also have the impression two modules that are not totally identical will sometimes work in dual channel mode. Is this correct?

I guess I could buy one module and install it and see whether they work in dual channel mode or just work in single channel mode to provide a total of 8GB of RAM. If they do not work in dual channel mode, I could then decide whether it's worth buying another module identical to the one just purchased.

The computer performs well with 4GB for tasks I've been using it for so far. But, I'm thinking of installing a virtual machine software and creating one or more virtual machines. Thus, the interest in adding more RAM.

 

Same size modules, but the rest doesn't matter.

 

Well, l hope that works. Here's a comment copied from Kingston.com:

I guess they may be advocating the surest/safest case, from their perspective, which is understandable. I wish they provided more product details. http://www.kingston.com/us/memory/s...=3&Mfr=HEW&Line=Pavilion Notebook&Model=82711 shows two 4GB products for my computer there's no detailed spec info to distinguish between the two products.

 

As long as the size (and to a lesser extent, speed) is matched you will be OK. Matching modules to exact details is really only going to help people who overclock their computers to extreme degrees.

Matching speed is a good idea as it will make sure the memory runs at the maximum speed possible, as if you install mismatched speed sticks the memory will run at the lower speed.