^^^Depends on a lot of things....but mostly if its been bought in the last 1-2 Years it would be a 300-400Watts SMPS with worthless ratings of the rails....
I would say whatever keeps your boat floating, though ofcourse will never say that these generic PSU's are 'OK' because any sorta power fluctuation, load on the PSU may kill the PSU as well as the components of the computer. Look out for atleast the cheaper Zebronics(Platinum Series is it?), CM and Corsair PSU's to be safe
^^ stay away from the zebby platinum series. Your best bet currently is the EXTREMELY hard to find Powersafe 400Watt Silver or the easily available Zebronics Pro Series 350watter for about 1.5k