• Which fan connector?

    From Percival P. Cassidy@21:1/5 to All on Tue Aug 28 18:30:45 2018
    XPost: alt.comp.hardware.pc-homebuilt

    I have an Asus Prime Z370-A motherboard that has several different fan connectors, but only two for "Chassis fans."

    I have the top and rear fans connected to CHA_1 and CHA_2, respectively,
    but I am wondering whether to connect my two (non-PWM) front mounted
    drive-bay fans to one of the other on-board fan-connectors or whether to
    just power them from a Molex connector.

    The currently unused on-board connectors are CPU_OPT (intended for
    dual-fan coolers, I think), AIO_Pump (which does not seem to have any
    kind of speed sensing control, and M.2.

    Suggestions?

    Perce

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  • From Paul@21:1/5 to Percival P. Cassidy on Tue Aug 28 19:48:48 2018
    XPost: alt.comp.hardware.pc-homebuilt

    Percival P. Cassidy wrote:
    I have an Asus Prime Z370-A motherboard that has several different fan connectors, but only two for "Chassis fans."

    I have the top and rear fans connected to CHA_1 and CHA_2, respectively,
    but I am wondering whether to connect my two (non-PWM) front mounted drive-bay fans to one of the other on-board fan-connectors or whether to
    just power them from a Molex connector.

    The currently unused on-board connectors are CPU_OPT (intended for
    dual-fan coolers, I think), AIO_Pump (which does not seem to have any
    kind of speed sensing control, and M.2.

    Suggestions?

    Perce

    The fan headers look equally functional. There's six 4-pin
    connectors with PWM and RPM. The 5 pin has signals for PWM
    and RPM for two more fans (but no +12V), intended for external
    fans of some sort.

    https://dlcdnets.asus.com/pub/ASUS/mb/LGA1151/PRIME_Z370-A/E13271_PRIME_Z370-A_UM_WEB.pdf

    If you went by the electrical information they provided, it
    looks like a total of 8 channels worth. They can do this, because
    they're getting these channels "for free" from somewhere. Maybe some
    on PCH, some on SuperI/O or something. In the old days, they
    didn't like to make "controlled" headers, because it cost
    a pass_transistor for each one. These headers today only
    contain logic signals (plus raw power). Only the gold header
    pins cost money in a sense.

    None of those headers should be modulating +12V. The +12V
    should be straight thru. The PWM signal enters the fan
    hub, and sets the speed at that point. Rather than the
    motherboard having any voltage related circuits on board.

    If it's more convenient, you can run the drive bay fans
    off a molex. Not every fan has RPM output, so some fans
    can't be monitored in any case.

    Looking at the BIOS screen, might hint that
    what's in the manual is "fake" or not. You might
    take your queue from what you see in there. Or
    if Speedfan doesn't list everything, then some
    of the headers might be four pin... but with
    no electrical connection to RPM or PWM. That might
    happen if the hardware didn't happen to have that
    many signals just "lying around".

    Paul

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  • From Peter Johnson@21:1/5 to Nobody@NotMyISP.net on Wed Aug 29 16:32:48 2018
    XPost: alt.comp.hardware.pc-homebuilt

    On Tue, 28 Aug 2018 18:30:45 -0400, "Percival P. Cassidy"
    <Nobody@NotMyISP.net> wrote:

    I have an Asus Prime Z370-A motherboard that has several different fan >connectors, but only two for "Chassis fans."

    I have the top and rear fans connected to CHA_1 and CHA_2, respectively,
    but I am wondering whether to connect my two (non-PWM) front mounted >drive-bay fans to one of the other on-board fan-connectors or whether to
    just power them from a Molex connector.

    The currently unused on-board connectors are CPU_OPT (intended for
    dual-fan coolers, I think), AIO_Pump (which does not seem to have any
    kind of speed sensing control, and M.2.


    I have the Z370-Pro version of this board and have a fan connected to
    the AIO_Pump connector without any issues.

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  • From Percival P. Cassidy@21:1/5 to Peter Johnson on Fri Aug 31 21:14:07 2018
    XPost: alt.comp.hardware.pc-homebuilt

    On 8/29/18 11:32 AM, Peter Johnson wrote:

    I have an Asus Prime Z370-A motherboard that has several different fan
    connectors, but only two for "Chassis fans."

    I have the top and rear fans connected to CHA_1 and CHA_2, respectively,
    but I am wondering whether to connect my two (non-PWM) front mounted
    drive-bay fans to one of the other on-board fan-connectors or whether to
    just power them from a Molex connector.

    The currently unused on-board connectors are CPU_OPT (intended for
    dual-fan coolers, I think), AIO_Pump (which does not seem to have any
    kind of speed sensing control, and M.2.

    I have the Z370-Pro version of this board and have a fan connected to
    the AIO_Pump connector without any issues.

    I was so pleased with the quietness of my 140mm top and 120mm rear
    Noctua fans and was getting annoyed by the whine of the Antec fans
    pushing air through the drive bays that I replaced those by 120mm Noctua
    fans as well. Since these are PWM fans, I have connected them to the M.2
    fan connector (I do have an M.2 drive, but it is running plenty cool
    enough -- 29C -- not to need a fan blowing directly on its heat sink --
    and it catches some of the airflow from at least one of the drive-bay
    fans anyway). And I discovered that I can specify which components' temperatures influence the M.2 Fan's speed, whereas the AIO_Pump's speed
    is controlled (contrary to what I posted originally) only by the CPU temperature.

    Perce

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