AMD Ryzen scales better with faster memory (though this is more true for the first-generation Ryzen like the R5 1600), for so than Intel Core does. I'd recommend 3200 MHz, as a start. Do you what speeds your RAM is right now? If you want to upgrade your GPU, see what the new Navi are going to be like in July. I'd imagine some price cuts will start then. Your system is pretty balance, good for 1080p and 1440p gaming.