Buying 2 Dual Channel kits or one Quad Channel kit

[Kataklysmic]

Looking at building a new PC soon and was wondering about any compatibility issues or performance issues with choosing one over the other. If I want 32GB of RAM, how much of an issue will I have buying two kits of (2x8) dual channel RAM and installing them together versus one kit of (4x8) quad channel memory? The reason I'm curious is because buying two matching sets of 2x8 is a lot cheaper than buying a matched set of 4x8. I know from the factory the quad channel kits are supposed to be guaranteed to work together, but lets say I decide to get one 2x8 kit now, and one later as an upgrade...will I see any performance hits or system crashes?

 

[geofelt]

What will your motherboard be?
Intel and ryzen will only operate in dual channel mode, regardless if the motherboard has 2 or 4 slots.

Next thing, only buy a single kit.
Ram must be matched and disparate kits/sticks will not be supported and will not always run.

What is your plan B if you later buy a second 2 x 8gb kit and it does not work with your old ram??

Buy a 2 x 16gb matched kit up front.

 

[Kataklysmic]

My motherboard will be an Asus Prime Z370-A. So basically, if I want to use all the RAM channels on my mobo, I need to buy all 4 sticks upfront? As in...if I want 32GB at some point, it would be better to go ahead and spend money on a matched 4-stick set instead of buying a dual channel set of 2, buying the same exact 2 later on, and then adding them to the existing ones?