Per your manual (http://dlcdnet.asus.com/pub/ASUS/mb/SocketAM3+/M5A99X_EVO_R2.0/E8044_M5A99X_EVO_R2.pdf), the USB 2.0 ports on the motherboard are on the bottom edge (USB910, USB1112 & USB1314). The 4th one is only for USB 3.0 ports.
If the cable from your case's top don't reach that far, you might have to look for an extender or something.