That's a dual rail PSU. You don't need as much amperage on each rail because you will have less components plugged into them. The user manual should tell you how to differentiate between the two rails. Ideally you want to power certain components on seperate rails. Mobo/GPU, GPU/HDD, Opticle Media Drives/GPU. Something like that. Maybe the GPU by itself because it takes the most power of any other component in your system.

Have fun with your new system... after you put it together. Of course Windows will ruin the experience.