Sunday, September 18, 2011

AMD SB850 SATA controller vs eSATA port multiplier

Last year, I bought three 4-drive eSATA enclosures from SANS. They each come with their own PCI-E eSATA controller card with a Sil3132 Silicon Image controller.

So far, this is the only SATA controller I have ever found that can recognize multiple drives in this enclosure.

The list of the controllers I tested that failed is long :
- Intel ICH9R built-in to my GA-P35-DS3R motherboard
- Promise TX4302
- VIA VT6422 PCI card (technically SATA, not eSATA)
- Gigabyte / J-Micron

And now I can add the AMD SB850 built-in to my GA-890GPA-UD3H motherboard.
What's interesting about this latest controller is that AMD claims port multiplier support with this chip.

And indeed, the BIOS can see multiple drives if I boot with the enclosure connected.
But after the OS boots up (Win7), it only recognizes the first drive in the enclosure.
Very frustrating. I hope someone at AMD is listening. I am using the AMD AHCI compatible driver version 1.2.296 dated 4/15/2011, under Win7 x64.

I tried designating the port as "ESP" in the BIOS, but the only difference that makes is showing the "Eject" icon in Windows. It doesn't help recognize the extra drives in the enclosure.


  1. I had roughly the same problem and found only one post somewhere with the correct answer to this problem.

    AMD AHCI does detect all drives in the bios but the Windows AMD Sata controller driver does not detect all drives...only the first one.

    The sollution was to set RAID in the bios and reinstall Windows. Now Windows will detect all my drives in the eSata enclosure. Yes, sadly you need to reinstall Windows for this because switching from AHCI to RAID is not possible....Not in an easy way that is.

    Motherboard : Gigabyte GA-A75M UD2H
    OS : Windows 8 (WIndows 7 also works off course)

    1. Thank you very much for your reply. I may look into it.
      However, I am not running a RAID setup.
      I have an SSD for booting Windows.

      I have measured performance between the AHCI and RAID driver, and the RAID driver performs significantly works than the AHCI driver for single drives in terms of latency. This shows up in disk benchmarks I have run before. So, I would like to avoid using the RAID driver unless AMD is going to fix the performance.

  2. Have you seen that - - on the AVS Forum?

    It seems that some strange combination of BIOS AHCI setting + AMD AHCI Compatible RAID driver can do what you want...