Many newbie after purchase high end PC part doesn't care about power supply as result GPU hard disk and parts get damage or get dead. The power supply delivery power according to the need of PC parts but some power supply..
All power supply are not capable of giving all kind of power. For example a 450 watts PSU can power a PC that require 500 watt power. Now many you can tell that this is easy math whats so new about it. but in reality many of new pc builder doesn't know about the maximum power usage of a PC. To know the maximum power usages. All you need to google every parts about how much it consume power and summation it all together and walla you get the maximum power usage of your PC.
Now You don't have a GPU. You only work with the CPU only. You may think that a 200 watt cheap Power supply will do the work but there some issue with cheap power supply. You system can work using 200 watt Power supply but your processor must not consume more than 30 watt and there should be only 1 storage and one single case fan. if this limit is cross then PC parts or PSU may get burn. So I will suggest get a minimum 450 watt non 80+ certified Power supply at least.
Now if the range is 250-280 watt then a 450 watt 80+ bronze will do the work.
To find the right you must get at least 100 watt more than your actual use. example:
if your PC use 300 watt then get 550 watt or 450 watt and if it cross to 350 to 400 then a 550 watt or 650 watt power supply and obviously 80+ bronze or sliver rated for higher power consumable get the gold rated power supply
at Today's perspective 550 watt 80+ Bronze certified are best for mid range gaming PC