Please help me with my PSU

Tier 1, the best-
http://pcpartpicker.com/parts/compare/evga-power-supply-220g20550y1%2Cevga-power-supply-220gs0550v1%2Cfsp-group-power-supply-pt550m%2Cxfx-power-supply-p1550bbefx/

Tier 2, second best-
http://pcpartpicker.com/parts/compare/antec-power-supply-hcg520m%2Cseasonic-power-supply-m12ii520bronze%2Cxfx-power-supply-xfxts550w/
 
Newegg lists the Photon-550 as the successor to the Capstone-550. Capstone might not come back in stock. You can check the link in my sig for a list of PSUs organized in tiers by quality. Any good EVGA/Seasonic/XFX should do the trick.
 




That antec psu seems within price range but it's 520W will that still work with my build?
 


Basically it means how much you can take the PSU apart. As in, adding the cables you want, removing the ones you don't. It's usually more expensive, but more aesthetically pleasing inside your case.
 
non-modular = All cables are attched to the PSU and the ones you don't use have to be crammed somewhere out of the way.
semi-modualr = Only the main cables you need are attached and some optional ones are not giving a cleaner look with less clutter.
full-modular = No cables are permanently attached. You use only the ones you need/want. Cleanest look.