Expanding ram

[MKeefeus]

So I am currently running 8gb of ddr4, but am starting to run into situations where thats not enough. The ram I have now is this https://www.amazon.com/gp/product/B013J7PF5K/ref=oh_aui_search_detailpage?ie=UTF8&psc=1  and I want to add more ram, but that particular kit is a little expensive compared to some others, and my CPU cooler is semi blocking one of my ram slots, so I have 2 questions. 

1) Do I need the same RAM, same speed, or neither

 

2) Would I have an issue adding 1 more 4gb or 8gb stick rather then running a dual channel kit

[Dankk]

1) both (recommended)

 

2) you need a pair (recommended)

Edited April 29, 2018 by Dankk
needed to clarify

[WoodenMarker]

If you use a faster or slower kit of ram, your ram will run at the lower speed of the two. 

Even though it's likely to work with different kinds of ram, you're less likely to run into issues using the same ram kit. 

Adding a single 4gb or 8gb stick can still work but it increase the chance of having issues.

 

Since your cooler is blocking a slot, it's probably easier to move to a 2x8gb kit and sell your current kit off. It shouldn't be too hard since ram is always needed and lifetime warranty sticks with the kit. https://pcpartpicker.com/product/4QNypg/team-vulcan-8gb-2-x-4gb-ddr4-2400-memory-tlgd416g2400hc14dc01