Here's a close-up view of the +12V rail selector. Notices that there was also a blue LED located near the +12V rail switch. The reason we have the +12V rail switch is because users can choose to combine or split the rails. At default, the TG580-U15 comes with dual +12V rails which support a maximum of 20A for each rail. If you are an avid overclocker, you'll know that having 20A on the +12V rails isn't going to help you push your system to its limit. This is where the +12V switch comes to play. Set it to �Combine� mode and the power supply automatically merges both +12V rail into a single +12V rail, which pumps out a whooping 35A! Although combining the two +12V rail should result in 40A, Tagan cuts out 5A to keep the power supply stable under high loads. Another reason why Tagan went with this design is because Intel's latest ATX2.0 specification requires dual +12V rails. This �Split or Combine +12V Rail� feature gives you to select what you want. It's like having two different power supplies built into one.
