littleleo :
Yes, Seasonic is a very highly rated power supply and they do OEM many different models for other brands out there. That isn't the issue, the requirements say a 600w power supply not 550w that is the issue.
You don't seem to understand power requirements very well. Watts
do not matter as much as amps. Specifically amps on the 12v rail. A high quality power supply will deliver a large percentage ( up to 100% ) of it's power rating on the 12v rail alone since that is the most important and most used rail.
A GTX 580 needs 40 amps on the 12v rail. Since amps x volts = watts you can see the XFX unit SR-71 recommended delivers 44 amps on the 12v rail for 528 watts of it's 550w rating. The Corsair CX600 in addition to using substandard Chinese made capacitors ( The sub 1000w EVGA units do as well ) only adds 2 amps to that for 46 amps on the 12v rail. Meaning although it's rated 600w it only supplies 552 of those watts on the 12v rail. The XFX supplies a higher percentage where it matters and more than exceeds the 40 amp requirements of the GTX 580.
So there is no issue. Don't unselect best answers when you don't understand the basics in the future please.