About memory, do I need the exact same brand stick in all slots? or?

So I currently have 8gb of ram, and I am thinking of getting another 8 gb, do I need to get the same brand? or will any brand do as long as its the proper speed for it? Also is it safe to mix ram speeds? This is the current stick I have: Crucial Memory CT8G4DFS8213 8GB DDR4... CT8G4DFS8213 from Mike's Computer Shop > PARTS & UPGRADES > Memory so do I just need another ddr4-2133 stick? Or should I stick with the same brand? Here is my motherboard. I really should have gotten the 2.4 ghz ram insted I suppose MSI Desktop Motherboard - Intel... B250 PC MATE from Mike's Computer Shop > PARTS & UPGRADES > Motherboards

Don't think matching matters much on the whole - just get the same (or faster) speed as it will run at speed of the slowest.

RAM Performance Benchmark: Single-Channel vs. Dual-Channel - Does It Matter? | GamersNexus - Gaming PC Builds Hardware Benchmarks

No one can give you an unqualified answer as to certainties that will work with your particular MOBO.

As that will be one of a pair then you should buy as near to the same that you can get, otherwise it may flip in to single channel mode.
Does not matter much if it does as I guess you are in single channel anyway with one 8GB module.

Originally, ideally, you should have bought a pair(kit) of two RAM modules. Then another kit of two to expand.

In theory it should work - the BIOS/UEFI would look at the SPD on all the DIMMs and choose the timing parameter values that are compatible with all the DIMMs (i.e the slowest values).

However, since it's infeasible for manufacturers to test every possible permutation of timing values, each manufacturer has their own set of "preferred" timings that they validate and program into the SPD. If you mix-and-match, your faster DIMM would be running at the slower DIMM's timings, which the faster DIMM's manufacturer may never have tested.

So using mismatched DIMMs will generally work fine but the behavior would depend on the specific DIMM manufacturers and your motherboard manufacturer.

Hi,
You should get a kit for how ever much you want
Being it is crucial just get it from them seeing they has a 100% compatibility claim and also their own it should be easy.
Crucial System Scanner | Crucial.com

Thanks all. I'll just get the same stick I had orignally then and pop that in the other slot.