So is this good or no ebay item number 323777004175There is a reason for them recommending other PSUs than what you are proposing buying. You should start to realize, cheap used PSUs are not something most would recommend for a card like a 670.
A CX500 wouldn't bee good enough new for longevity, let alone a used one that may have been hammered for years.
I have already explained. The old VS and CX are garbage. Even that S12ii is old, but reliable.
An s12/m12 is not overkill for anything these days and Its not very expensive either.
Sure nvidia may reccomend 500w, but can a cx500 reliably deliver the power needed to support that card? Maybe. Too many unknowns with used.
I would trust a new VS gery 550w more than a used green CX or orange VS. And i wouldn't ideally want to use a new VS, but it wouldn't be a fire hazzard at least.