Games crashing on new computer.

2 weeks ago I decided to buy the parts for a pc of my own with components that I chose for myself, Motherboard: Asus prime b650-plus, Processor: Ryzen 5 7600, corsair vengeance 32gb ram, GYGABYTE Geforce RTX 4070, 1tb storage, and a NZXT Kraken 240 Liquid Cooler. I installed Windows 11 on it, I activated XMPs and the frequency should be set automatically to 5200 which is what it is in the box. At the beginning, when I played games such as Fortnite, Warzone, Roblox, everything seemed fine, however I installed Rainbow Six Siege and it started to crash, a few hours later, I noticed that Fortnite started to crash also, saying :"Fortnite has crashed. We're very sorry this happened and we are working towards preventing it in the future. You can get help online at Fortnite Technical Support." I then moved to Warzone where it started to crash too and before I knew any other solution, I just force turn off the computer by holding the power button, a few days later I realized I could open a new desktop when Fortnite crashed and open task manager on it and end task, however, I could not do this with Warzone because it wouldn't let me open anything and I had to force shut down. I proceeded to reset my whole pc and start from 0 since I didn't have anything important in this computer and that way check if it had anything to do with the files that were causing the crashes but after setting everything up and downloading Fortnite to test this, after 15-20 minutes of playing, it started to happen again. I thought it had something to do with the thermal paste later on and I decided to change it so I bought new thermal paste and 91% Isopropyl alcohol to clean the cpu and the liquid cooler, after doing this and turning the computer on, I tried playing fortnite again and I downloaded Rainbow Six Siege again to try both, but after 15-20 minutes of playing, again, it started to crash. I'm starting to believe this could be a technical error meaning I did something wrong when building the PC but I'm not sure because I don't think it would even turn on but I wanted to ask here first and see if anyone knew what's going on.

:)