aspahic1 :
Everyone say it is good but why there isn't many review on the net and there are ton of corsair cx stuff? and why XFX Core Edition PRO 550W has 2 CPU connectors?!
There aren't as many reviews of the XFX because people get really into "Oh this brand is fantastic!" rather than noticing that each lineup varies in quality. Corsair had a long run of only having good solid units out there so they are still commonly recommended even though in most cases you can find an XFX unit for less that does as well or better.
The CX series is corsair's entry lineup, its priced that way and has parts to match. They are rated at 30C instead of 50C like a high end unit and only pack a 3 year warranty, the warranty is a good measure of how long they expect the unit to last.
The XFX unit is rated at 50C, provides a 5 year warranty, and has significantly greater capacity than the CX 500, more so than their nameplate ratings would suggest. The XFX 550 has 44A on its 12V rail, the CX 500 only has 38A.
As for reviews of them, the only CX PSU to get a real review has been the CX430 but not even the current CX430. The XFX was reviewed, it did well aside from wonky 12V performance during crossloading which isn't something that occurs without you intending for it to.
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story3&reid=225
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story5&reid=239