I always do a backup and then a clean windows install using media creator tool when I'm upgrading any component which operates with drivers (GPU, network cards, etc). It just takes me around 45 to 60 minutes to get everything up and running and one more hour to restore the files. 2 hours in total, and I save days diagnosing faulty drivers or bad instalations
You can use THIS tool from Cooler Master to check how much power u actually need in your system. Just input your devices on that calculator and thats it!
EDit: Alternatively if Cooler Master's calculator is down, you can use THIS ONE from be quiet!
NOTE: Almost every single RAM and SATA Device consumes practicaly the same wattage, so don't worry if u think the be quiet! tool is not complete. What actually matters when calculating PSU wattage is CPU, GPU and cooling solution (if u have water cooling or not. This pumps can get really power hungry), then add somewhere around 100 watts for SATA, RAM, Motherboard, etc. Also dont pay attention to what the manufacturer says about the recommended PSU because they dont even know what CPU you have. They say 750 watts just to make sure that no matter what CPU u throw at it, it will run ok, for example if you have a 2990wx, paired with a Vega 64 (which recommends 750 watts) the wattage needed its somewhere around 700 to 750 watts. Having in mind that the 2990wx with TR4 taichi motherboard consumes somewhere around 350 watts, having an i7-8700k and its motherboard which consumes around 150 watts instead the 2990wx consuming 350, you will have to push 500 to 600 watts, instead of the 750 AMD claims vega 64 needs, or those 700-750 that 2990wx needs to run. So Yes, if your CPU is at or under 95 TDP, you shouldnt have any issue at all about power