you can still use the same psu without any issue the reason is
GTX 950 =90W
GTX 1050 = 75W
RX460 = 75w if you are going to overclock you should buy a psu around 600w
as i see you have a core i5 4430 Processor so this is a non K processor so you can't overclock this and yes 600w more than enough for your need if it 80plus rated.