This is my first PC being built, you can criticize all you want but I already bought the part & reuse some other parts like the RAM & Storage, I just want to make sure what Power Supply I need for my Build? I've checked on many websites about Wattages, most sites estimated usage around 200W-300W but GPU ask for the minimal of 400W, I'm just confused as to what Power Supply I need? Should I get 500W?
My PC List: http://pcpartpicker.com/p/m2PFhM
get 500W as it gives you room for future upgrades etc... not much, but its something.
(yes, the estimate is correct, gpu makers always write more than they really eat)
So is the minimal 400W still good enough? Since you mentioned it doesn't really use more than it really eats.
you should be good with 400, but be sure to buy good one, not some cheat cheap that does even less... like 200 in reality while its advertised as 400...
Just about the cheapest thing you should buy is this evga unit but if you can spare a bit more look at this one
Avoid that eXtreme range of psu's like the plague. The only extreme thing about them is the poor quality.
You dont really have to splash out on gold etc rated units just be sure that its from oem that is good.
for example XFX uses Seasonic. For which a dirt cheap one like this >>
http://pcpartpicker.com/part/xfx-power-supply-p1550gts3x
For <$60 it buys piece of mind more than anything. Will handle a nice and powerful single gpu later on as well.
I would advise listening to @deejeta as his recommendation and @anon5205053 are correct. You want a higher quality unit then that cooler master eXtreme, that unit isn't very good and has a high chance of a short life and that may result in it taking parts of your system with it when it dies.
As for the amount of overhead consider variables such as wear as well, capacitors don't stay at full health forever. Over the years they weaken a power supply that did 500w might do mid 400s after a time. As well as the listed wattage is the maximum, you don't want to run a PSU at full load all the time so factoring that in is a good idea as well
Overall, I'd say that XFX TS 550W @deejeta suggested would be the optimal choice