I am building on a Asus P6X58D and I noticed to my pleasent surpise 6 memory slots. Hmmmm.
I have 3x2GB memory modules coming from corsair, don't remember exact model, but is says it will support 1600.
Can I add 3x2GB more modules for 12GB? Or, can I add 3x4GB modules for 18GB?
I understand that the modules have to be installed three at a time for the best performance, that is what triple channel is I suppose. But it has been a while since I built a system, and never saw one with more than 4 mem slots....so 6 is quite nice.
The total density (GB) you can install is a matter of what the limitation of your particular mobo is. Chances are, though, you won't need to have more than the 6 GB. In fact, 6GB is already plenty of RAM for even larger multitasking.
And yes. Installing RAM modules in sets of three will enable your triple channel.