Sata 2 or 3?

[Raxbar]

So recently my friend gave me a used drive that I plan on using as a backup drive. However, I own a GA-Z77-D3H motherboard and have already used all of the native Sata 3 slots. I was wondering. Should I plug this sata 3 compatible hard drive into the marvell controlled sata 3 or the chipset controlled sata 2?

 

[popatim]

either one. Mechanical harddrives cannot exceed sata2 speeds yet.