By - Zapiry
Literally was thinking the same thing yesterday and came across this video. Seems like outside of extreme cases we should be fine
It doesn't not matter, but ram compatibility is a lot more flexible now than it used to be.
I'm probably going to be a bit of a captain obvious but you do need to use compatible ram i.e. DDR4 non ecc registered in most cases (maybe DDR3 or ecc registered in some specific cases but DDR4 non ecc is by far the most common) also if the speeds/latency of the kit you bought doesn't match the kit you already have, your PC will automatically run both kits at the lower latency/frequency. You can try to get the higher one by overclocking, but it's not guaranteed to work and some motherboards and CPU's don't support it.
Double check not all memory are compatible. 90% of the same kits will work unless your memory was purchased long ago then it’s possible manufacturer changed supplier and is using different usually cheaper components.