Usb3_34 and usb_12?

[xElevationsx]

Hello, this is my first build and I'm plugging in cables that came installed with my 760t v2 case, I've just noticed that it looks like my usb3 cable will plug in to the sockets labeled on the motherboard usb_32 & usb_12 what's the difference and which should I plug in my cable? Thanks!

 

[clutchc]

The usb3 cable from the front of the case should connect to its own usb3 header on the board.
http://techreport.com/r.x/2011_8_16_Fractal_Designs_Define_R3_midtower_chassis/usb3-620.jpg
It should not connect to the usb headers.