You can try as above or get this http://www.newegg.com/Product/Product.aspx?Item=N82E16816124045
and bypass the onboard SATA connector. The card is bootable and will allow you to connect up to 2 SATA 6gb drives to it. It uses a PCI-E 1x slot and runs about $22.
I am using one in my system because all 6 of my onboard connects are in use and needed 2 more to setup the system to boot into Hackintosh OS X 10.8.2. It works very well and supports hot swap hot plug Multiplier and Trim support.
It would allow you to use your GPU and bypass the onboard SATA connectors all to gether.