Stefan Mileschin

Intel's X79 chipset for Sandy Bridge-E platform was originally designed to have four SAS (serial-attached SCSI) channels apart from its usual loadout of SATA ports. Early prototypes of socket LGA2011 motherboards displayed at last year's Computex event (June), carried a large number of chipset-driven ports. However, Intel found the chipset-integrated SAS RAID controller (independent device from the SATA RAID controller) to have "unreliable performance", and hence changed its specification at the last moment. So the production specification of X79 ended up having the same SATA port loadout as P67 (two SATA 6 Gb/s + four SATA 3 Gb/s).

This specifications change did not result in a design change of the X79 PCH package, its die remained the same, so did its package and pin-map, which motherboard vendors had for nearly an year. So ECS decided to implement the SAS ports despite being out of specifications. LegitReviews discovered that its X79R-AX sample very much did have SAS ports wired to the PCH. With firmware of the SAS RAID controller and drivers, it could enable and use those ports. Although the SAS ports are physically present on the board, users have to enable them via the UEFI firmware setup program (BIOS).

http://www.techpowerup.com/158917/EC...therboard.html