the mininum is dictated by the rest of the components and decision to limit future upgrades down the line.

after you are aware of what cpu you are using

amd and intel sub 250 cpus usually 150w or less

amd high end and alderlake(12gen, and arrowlake), peaks at 250w

intel raptor lake (13-14th gen) 300w

hedt cpus like threadripper fall under a similar class.

peak 5060ti is just under 200w alone.

add an arbitrary 50w to cover rest of components.