Nuvoton NCT6776F Does Not show 3rd Fan

Do you have the latest BIOS?

On 02/17/2017 12:43 AM, actionparsnip wrote:
> Your question #464121 on Ubuntu changed:
> https://answers.launchpad.net/ubuntu/+question/464121
>
> Status: Open => Needs information
>
> actionparsnip requested more information:
> Do you have the latest BIOS?
>
The BIOS is up-to-date. The BIOS displays the 3rd fan speed correctly.

On 02/16/2017 06:53 PM, tomdean wrote:
> New question #464121 on Ubuntu:
> https://answers.launchpad.net/ubuntu/+question/464121
>
> I have an ASUS P9X79 Pro mother board with three fans attached.
> The BIOS shows 6 fan slots, with 3 having values.
> I can find two fans in the NCT6776 at
> Bank 6 Address 0x58/0x59 and 0x5a/0x5b, (hi/lo bytes).
> But, no other address in the NCT6776 banks shows a correlated change in value when I disconnect the 3rd fan.
>
> Any ideas?
>
>

My BIOS is
         Vendor: American Megatrends Inc.
         Version: 4801
         Release Date: 07/25/2014
         BIOS Revision: 4.6

Looking deeper into my fan connections shows some interesting capabilities.

Only two of my fans are connected to the Nuvoton NCT6776F chip. The
other fan connectors appear to be connected to the Intel X79 chip.

I read all the registers in the nct6776f chip and only two places show
values that correspond to disconnecting fans. Many register values
change +- 10% or so each time I read the registers.

dmidecode shows 6 fan connectors with reference designators identical to
the names used in the P9X79 datasheet.

This leads me to believe that BIOS is accessing two of the fans through
the nct6776f chip and the other 4 fan connections through the Intel X79
chip.

Is there any to access the BIOS functionality corresponding to the
handle reported by dmidecode?

For example,

Handle 0x001E, DMI type 8, 9 bytes
Port Connector Information
         Internal Reference Designator: CHA_FAN2
         Internal Connector Type: Other
         External Reference Designator: Not Specified
         External Connector Type: None
         Port Type: Other

Tom Dean

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