Yes, should be fine. Corsair RM850x is a very good PSU for price. But make sure it's 2021 model, not 2018 model. Any good quality PSU will do and 850W is definitely at very minimum at least for 4090. But 4080 should be perfectly fine with either 750W or 650W PSU as long as it's quality psu, not cheap 750W PSU. I've used a Corsair HX850 for many years and worked fine with my old Vega 56 that is over 300W TDP card. Heck, 4080 don't use much power unlike my Vega 56. So I could imagine it would works with low wattage PSU like 650W. Again, just make sure it's a really good quality PSU. Never get any cheap PSU. I plan to undervolt my 13900K and 4090 eventually...just need to find the time to do it. haha.Will a decent 850w be enough? Or is that too risky? Corsair RM850x....for e.g.