Adding a SATA HDD with no SATA ports nor PCIe slot?

Four-channel SATA III PCI-Express controller with two internal SATA ports and two slots for SATA disks Standard & Low profile

You would probably need to use the PCIe slot if you have one free, but I simply don't know if the bus is fast enough

sata slot GIGABYTE solution offers considerably faster storage performance and support for both PCIe and SATA interfaces* for SSD devices * Supports only

sata 3 slot 3 x4 lanes of up to 4000MBs Not to say that speed is 2 SATA is just a complete wasted