High-End PC Lags HORRENDOUSLY playing high end games with no resources maxed?

PC Specs:
Running Windows 11 Pro
CPU: Intel(R) Core(TM) i7-14700K 3400MHz
RAM: 64GB (16gbx4) DDR5 Corsair Vengeance 6400MHz
GPU: NVIDIA GeForce RTX 4060
Mobo: Z790 Gaming Plus WIFI
2x NVME SSDs (1Tb and 2Tb)
1x 3Tb HDD

I upgraded my PC about 1-2 years ago with the hopes of playing Tekken 8 and FFXVI with my wife as my original PC couldn't run them in a playable state. Fast forward to now; i've replaced essentially everything in my PC and yet when i'm playing any high end game (basically anything not an old JRPG on my library) it lags the REST of pc out HORRENDOUSLY while the game itself is choppy but playable. I can't even move my mouse on other monitors or type when I tab out. Trying to watch anything on a second monitor while I play has the audio playing fine but it's essentially a slideshow. I've tried replacing hardware, turning settings off, turning other settings on, reinstalling drivers, lowering settings in my games to as low as possible (which is frustrating from how much I've beefed it up to NOT have to do that) but even then it still is happening. I'm really at the end of my wits with this because I really have no Idea on what to do here.

During all of this too I've watched my temps and resources and neither get remotely close to being in a dangerous range. Temps sit around 30-40C and my resources haven't gone over 50% on anything when this is happening.

The last thing I haven't done that reportedly worked for other people is enabling XMP in the Bios however attempting to do that makes my PC fail to boot. So please if you have any suggestions please help me. I want to be able to play these games and stream them to my wife.