I imagine a good quality 650w is still fine. Its the overclocking that really would start to use up power, but just running the stock card even the liquid one is going to work.
Another factor with PSU is age, roughly the capacity declines by 10% a year apparently so maybe just use whichever PSU is the newest
Well the 650 is about a week old so should be fine if i decide to go for one, which I've really no need to
