Sleeved Extension Power Supply Cable

All of a sudden my PC started to shut down (instantly turn off) all of a sudden while playing Black Desert. I have observed that when Im doing simple task, it won't turn off but when I do heavy task like playing black desert, it will turn off in minutes so I have done some troubleshooting...

I'm wondering if i can use another modular psu cables instead of the used to ax850 cuz i have searched for them but didn't find anything Or if someone know where i can find them with the possibility of delivery

I have a G-Sync enabled monitor (Acer XB240H), and a compatible nvidia graphics card. In the nVidia control panel, G-Sync is enabled, but when I go in-game, the frame rate goes above the advertised "144 hz limit", and I am experiencing screen tearing. Any help in solving this issue will be...