I have a 10900k which has higher TDW than your 9900k I will be watercooling with my 3090FE and i bought an 850w after doing some research, should be plenty i believe.
Edit: Come to think of it I have a power meter on my main line and my whole house is only drawing 800w when I was overclocking the 3090 last night.
Edit: Come to think of it I have a power meter on my main line and my whole house is only drawing 800w when I was overclocking the 3090 last night.