holyprof :
I don't know what you have so please write your current configuration. I'm using the CX500M with overclocked i5-4690K and overclocked GTX960, maximum power drawn is below 400W in the toughest tests.
Motherboard - Asus Maximus VII Ranger
CPU - Intel Core I-5 4590
GPU - Nvidia Geforce GTX 770
If Your Configuration Takes 400w, Then 500w Will be Enough for me