S-SATA Vs I-SATA (PCH, SCU)

My mother board contains SATA-3 ports however some are listed as S-SATA and I-SATA as shown in the manual:

I have plugged some harddrives in each of these ports and they both work fine. However I want to know the difference between these ports and I'm having trouble finding the difference between PCH and SCU for SATA. My primary concern is if one type of port is faster than another.

Can someone please explain the difference between these SATA types?

Thanks

• SCU means Storage Control Unit
• SCUs support SAS drives with HDD enable module installed
• SCUs do not support Optical Drives

• There is no practical performance advantage when using SCU

• Intel PCH supports two types of RAID controllers: AHCI and SCU

• The thing listed as PCH is the normal AHCI mode.
• The AHCI controller supports SATA drives and the SCU controller supports both SATA and SAS drives (Exceptions exist, like the SCU controller for PCH C602 that supports SATA only).

What's important to remember is never to put ODDs on SCU. You have to put any Optical Drives on the normal AHCI (the I-SATA).

If you do use ODDs, put them on I-SATA and the hard drives on S-SATA (for a RAID up to 4).

If you do not use ODDs and you use normal SATA hard drives or SATA SSDs, it won't matter. In this case, you will be able to RAID up to 6 drives with the I-SATA and up to 4 with the S-SATA.

Conclusion: no speed difference.