Power supply problem

Full modular power supply, question is: Can i plug 6pin power cable for hard disks in place for 8pin for gpu?? Hii to all, im new to lemmy so exuse me if i wrote this in wrong category or something.. I have problem with ps, hard disks randomly stop working and i cant acess them, and when i disconect it and connect it again it starts working again. This doesnt happen wit ssds. Ps is radimax cobra 800w full modular. I suspect sector for sata ports doesnt work properly. Because i never had any problem with graphic cards, curently have rx 5700xt.