ASUS P8Z77-I Deluxe SATA port multiplier?

[QueBert]

I can never find much info on SATA port multipliers and which MB's support them. I'm interested in this for my new build, and that's a feature I'm after. The MB only has 1 PCI-e slot so I can't add a card. Is there some way to figure this out one MB to another without contacting the manufacture? I've contacted 3 so far and didn't hear back from any,