If you go to a ram vendor web site, you can access their ram selection app.
Most ram vendors have them.
Enter your motherboard and you will get a list of supported ram kits.
As to spending on a FX system, I suppose you could.
But, you will be buying ddr3 ram which is no longer used in current gen processors.
The FX cores are relatively slow, at least for a gamer.
If you are running batch apps, a FX-9590 with 8 threads, that is a much better case.