The motherboard manufacturers test their motherboards, to ensure that they typically work with overclocked memory modules.

If you buy a complete gaming computer which includes overclocked memory, then hopefully the vendor has done a burn-in and has tested for some time the computer, as sold.

However, if you buy the CPU yourself, neither Intel nor AMD provides any guarantee that the CPU will work with overclocked memory.

It is upon you to test your assembled computer, but true tests would require a very long time and a climatic chamber, to offer any kind of certainty that the combination CPU-DIMMs works at the desired speed.

If you have ECC memory, you can try to overclock it and at least in this case you will know for sure if the memory works at the higher speed, or not.

Overclocking ECC memory is actually a method frequently used to verify whether the hardware ECC support and also the operating system EDAC driver work OK.