Bad performance and fps on a monster pc

So i bought a 2000$ prebuilt asus rog strix g16chr g16chr with an intel i7 14700kf and nvdia rtx 4070 super with 64 gigs of ram, and was hoping to achieve around 600 fps in rainbow six siege. Problem is, even after trying every optimization and overclocking guide and enabled x.m.p in the bios and also changed my settings to high performance. I'm barely even getting 200 fps. I changed all the settings to the lowest and yet i still get many issues and also packet loss issues. It's really making me frustsrated and i was wondering if anyone could let me know what is causing this and why? Or I'm just going to try my hardest to get a refund from this pc that i spent 2000$ on and its shitty performance.

Edit: On cpu intensive games like fortnite, valorant, rainbow six siege, and other multiplayer games I'm having constant issues and shit performance, but on gpu intensive games like witcher 3, wukong, ghost of tsushima, Im getting 300 or more fps on ultra+ settings. Also in cpu intensive games I downloaded msi afterburner to check my stats in game and it says that my cpu ulitzation is around 30% and my gpu ulitzation is 60%. Is this some sort of major bottlenecking issue in cpu intensive games? Please help