Hi, I need some help!!!

[ShinyMinotaurs]

recently I have upgraded my most of the components in my pc cpu, ram, mobo, ssd and gpu and randomly my pc just shuts off completely then instantly after a complete shutdown turns on again. I have an older 650 watt silverstone psu that has seemed to be reliable so far. I also have quite and old case i dont have the specs for with only 2 working 80mm fans and a stock rx 5700 xt which runs really hot. The rest of my specs are i7 8700, 16gb hyperx fury ddr4 asus prime b360m-k and a 500gb 970 evo plus. I dont know if it is because my gpu is getting to hot (i have checked thermals and it idles at 50-55 degrees celcius and under load it goes to about 90+) or its another component. I know old cases can have dogy reset switches so i have unplugged that and not had any diffference. any advice would be helpful.

[DobertRownySr]

Buy a new powersupply. If your PC ever shuts down randomly 99% of the time, it's the PSU.