Both are very nice, what is the difference between a bronze and gold rank PSU? Does it warrant the 20-30 dollars? Thanks
In my opinion, no. But modular does make it a little bit worth it.
80 PLUS is a standard that rates PSUs according to their efficiency on given loads.
For example a 80% efficient 1000W PSU will draw 1200W from the wall socket to deliver 1000W, where a 90% PSU will only draw 1100W to deliver 1000W.
Here is a explanation : http://hexus.net/tech/tech-explained/psu/29911-80-plus-certification/