on my Sabertooth x79 MB, need to add an expansion card for extra sata 6gb ssd's. i'm looking on Amazon at the se:

"I/O Crest 4 Port SATA III PCI-e 2.0 x2 Non RAID Hard Drive Controller Card Marvell 9235 Chipset" and the
"I/O Crest 4 Port SATA III PCI-e 2.0 x1 Non RAID Hard Drive Controller Card Marvell 88SE9215 Chipset"

i have one PCIe 2.0 x1 slot open and one PCIe 3.0 x16_2 slot open. the PCIe 3.0 x16_2 slot is the one i should use, yes?

the 9235 chipset would be the one to go with, yes? i.e., the transfer rates would be better with x2?

tia