Why is it important to know which is which? They are all usb 3.0. If it's really important to know then you could delete the Asmedia controller in device manager and see which one works and then relaod the drivers from the motherboard cd.
Instead of deleting the controller just go into the bios and disable the Asmedia controller and then when your done enable it.
Sometimes it's just nice to know your new equipment. In this case I've read that Intel's SATA ports are preferred over ASMedia (or any other 3rd parties'), and I thought the same may be true for the USB ports.
You're test from bios is good, and obvious; feel guilty for not thinking of that. Thank you.
It's important to know which USB 3 controllers are the intel ones and which ones are the Asmedia ones because only the intel ones can be booted from. Important if you want to use a USB 3 stick to boot from.