Wow... this is interesting. Seems companies like Antec & Corsair don't actually manufacture some of the power supplies that they sell. Even more interesting is that Seasonic seems to be a major supplier for many of those companies. Check it out:

"More and more traditional companies from other segments are entering the PC power supply market. However, the majority of them actually don’t manufacture their products. In this short tutorial we will teach you how to find out who is the real manufacturer of a given power supply."