Intel were originally planning of including Serial Attached SCSI (SAS) ports on the X79 platform but found that they were having issues with reliability or compatability so they disabled it. As Legit Reviews prepare for a full review of the X79-AX, they discovered that it had a full array of SAS ports and when contacting ECS they were told.
"As to SAS labeled, itís because originally Intel was going to support SAS connection on X79 chipset, but they hid this function in the end. However, since our MB layout already designed for this support, we decide to keep it. Due to Intel stopped on the project, so itís hard to guarantee 100% compatibility on every SAS device, we have to keep it low profile as just more SATA ports to promote it (even though in our test, most SAS storage are workable on these ports). Itís indeed supported by Intel X79 chipset, even though Intel doesnít announce to support either disable the function, the function are still in the chipset..."
The ECS X79R-AX
Highlighted SAS ports as Legit Reviews discover that they are still enabled.
While they tested to be inconsistent in performance, they worked. The feature comes disabled in the UEFI BIOS by default but can easily be enabled, at one's own risk mind.