I see.
My cousin assembled the PC for me, so I didn't know that. How exactly could you tell though?
They're color coded and that's what manuals are for. The mfgrs website will also clue you in to where the best ports are located too.
I'm not certain of the ASMedia ports interchange compatability level.. but generally speaking.. many 3rd party controller installs(like yours) can simply be swapped over to the Intel 6G port with out issue since the OS has all the default drivers needed inserted during any install.
Power down.. swap the sata cable to the Intel 6G port.. reboot.. and enjoy the faster 6G speeds.
Worst case is that it won't boot.. you choose not to repair so the OS doesn't freak out when you decide to power down and put the sata cable back onto the ASMedia port. Highly unlikely though as the bios and Windows is pretty smart these days.
