Ghz but rather the cache
I would say the quantity is important first, then the Hz number. If you only have 1GB, 4000MHz won't bring you anything… You need a good mix. But somehow 16GB or maybe 32GB is no longer worth it (unless you do something with it like e.g. Film editing) From mostly 16GB you no longer need for gaming then it is worthwhile to go to the Hz number
(It's all my opinion! Write me your opinion if you think I'm wrong.)
Both are equally important. If you have too little of something, then you have problems.
However, 16 or a maximum of 32gb doesn't cost the world now either and the processor is mostly the bottleneck.
This is important when using a software decoder
What should be meant by GHz? Frequency of the RAM or the CPU? Can be a lot that has to do with frequencies.
Of course, it depends on the purpose, if you play games with multithreading support, then you should have 8 cores (for example the Ryzen 7 3700X).
For modern games you should already have 32GB of RAM and a good CPU with many cores, because some games need more than 16GB of RAM anyway and the use of multiple cores supports almost every complex modern game.
