Why people here needs so big PC's is out of my imagination really. I do not get it at all. As for those processors - you really can go just with any you like and that's it. They are both more than powerfull for your setup. Forex do not need that much power.
It's got nothing to do with trading, per se. It has everything to do with graphics load and how that load is handled by your computer. If your trading (work) load has a lot of charts, your graphics load will be greater. If your work station has CNBC or some other streaming 'Net service, your graphics load will be greater. If your GPU is muscular, than your CPU can be 'mild'. (On the other hand...) If your work station is strictly for trading, and you have 1-2 charts open, you can probably get away with a freakin' phone and be just fine...
If you're primarily interested in gaming performance, you need at least a mid-range Intel Core i5 or AMD Ryzen 5 CPU. Considering that the graphics card is more important for gaming than the processor, you can save money by not getting a more powerful Core i7 or Ryzen 7 chip.