KingZam :
Wouldn't recommend that PSU if your planning on overclocking or turning your pc into a absolute overkill.
Neither of those two things is the point of this build,the only thing to really overclock is the gpu and that should be fine.With the "Z" motherboard could he make all cores run at max turbo,which is a kind of overclocking,but that should be fine too.Added the cooler to keep temps in check.
For these kind of parts and purposes is the 550watt enough and the quality of the psu decent enough too.Quality is alot better than the 500watt EVGA from the first build.Heck,it's even in tier one
here.
The third build just makes odd choices largely to get that expensive r9 380X in which as i said (imo) isn't worth the extra money.Same goes for the cpu cooler or psu (not as good as well,wattage is certainly not needed).Choice for the hdd,motherboard aren't as good too,well imo not.
I see that my build has gone over budget,but look for similar parts in the pcpartpicker.The gpu is more expensive now,something else to get it under budget again,.
http://pcpartpicker.com/part/xfx-video-card-r9380p4255
just to show what to look for