A 650W should actually be enough if the processor is not overclocked. It also depends on what else is connected. Otherwise, the PSU computer from Outervision can also be used. However, I generally always take 100W more than the computer outputs in order to be able to upgrade hardware in the future. https://outervision.com/power-supp...

I use a similar combination with 2 RX580 8GB and have therefore installed a power supply unit with 850W. This works fine even in continuous operation.

GK and CPU have a max TPD of about 180W each MB is mostly negligible so theoretically anything more than 450W should be ok practically I would say at least 550w so there is a certain safety margin. I bought a similar system a few days ago and decided on a 600W 80+ Titanium NT, unfortunately my case won't arrive until tomorrow :(
If you want to overclock or work with multiple GKs in the future, it's worth getting a stronger NT. My personal tip is not to save on the PSU - high quality affects your entire system (longevity) and your electricity bill (80 plus).

I'm not a crack, but I think 800 minimum. I decided on 1200w because the processors are very hungry (especially with OC).
PS: Ram should be chosen very well