To my belief marketing dual channel, quad channel memory is purely marketing. Only thing that matter is having the correct same amount that the mem controller needs
Two things.
1. two dual-channel kits, bought together, and used as a quad kit, may not operate as advertized. Chances are, yes, it will work, but there is no guarantee from the ram makers about that(every company will advise buying a quad-stick kit for population of four DIMM slots) . If you want to populate more than two DIMM slots, and want support for that config, you need ot buy a kit with the number of DIMMs you wish to install. Other configurations are typically not provided with support form teh memory manufacturer.
I have run into this issue myself, with two dual-channel kits not working well together, even under lower speeds. However, i have also bought two dualchannel kits and had them work just fine..it's luck of the draw.
2. Quad channel memory is intended for X79, and as such, features and XMP v1.3 profile, that also includes VCCIO voltage settings when XMP is enabled. A non-XMP v1.3 kit(ie. XMP v1.2 or v1.2) may not work as advertized in an X79 system, due to this lack of info for the BIOS to make appropriate settings, and also becuase of differences in sub-timings and drive strengths between platforms.
I have personally run into this problem, where installation of a dual channel kit, on it's own with just two sticks installed, failed to boot and be stable until manual adjustments to VCCIO andsubtimings were made. I will be discussing this(what happens, and how to fix it) in an upcoming review(not the samsung one).
So, to close, generally, you are correct, but there are instances where buying the right ram matters. In my "professional" opinion, it's best to be be made aware of all potential issues, and how to deal with them, rather than to blindly recommend everything will work, when it may not. I will always be an advocate of full disclosure when it comes to situations like this one.
