you have an awesome gaming pc, the only thing i see to increase performance is add another 1080 ti for sli but i don't know if you need it with the pg348q monitor. It depends on the games you play and how many frames per second you're currently getting if you'd want or need one.
Or you could keep what you have and overclock your cpu and gpu.
You should see how many frames per second you're getting, if you're hitting 100 FPS in your games you really don't need to overclock.
Do you have a program that shows FPS while playing games ?
Ok yeah tell us how many Frames Per Second you're getting, then if you want or need more I'll help you overclock if you like.
Well that's pretty good, you could overclock to see if you can hit 100 FPS.
You can start with your 1080 Ti, Chino made a guide for overclocking the ROG Strix 1080, you can use it as everything applies to your 1080 Ti.
Once you get your gpu overclocked then you can overclock your cpu.
I'm going to sign off, it's 2 am here in the u.s. if you would like help overclocking your cpu I'll gladly help you tomorrow. 🙂