P5Q Deluxe External USB/1394 Port Question

Discussion in 'Asus' started by me, May 5, 2011.

  1. me

    me Guest

    I have installed ports with two usb each to the blue headers on the mobo.
    One header has a red connector for the 1394 port. Am I better off not to
    connect to large drives to these connectors or does it matter? Should one
    drive be connected to one header and one to the other? Just wondering what
    would be the ideal way of doing it. Any difference in reliblity or
    performance? Thanks for the help.
    me, May 5, 2011
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  2. me

    Paul Guest

    In terms of hard drives, 3.5" drives tend to be powered from an AC
    power source. The startup current can be as high as 12V @ 2.5A, which
    is difficult to source directly from the computer itself.

    2.5" drives have lower power requirements. They may draw 5V @ 1A
    during spinup, or as low as 5V @ 500mA. In some cases, the manufacturer
    chooses not to state this transient current requirement, to the annoyance
    of their customers.

    Each USB 2x5 header, has a Polyfuse next to it. The Polyfuse is for
    safety (it's not a "current flow policeman"), and cuts the power to
    the header, in the event enough current is drawn to damage the pins.
    The Polyfuse might have "1.1" stamped on it on older motherboards,
    to give some idea what current could be drawn from a USB "stack of two".
    If only one USB load was connected, it might be able to draw 1.1 amps
    for a very short time, without the automatic fuse opening.

    USB officially support bus powering up to 5V @ 500mA. On some 2.5" USB
    drives, that is sufficient power to spin up the drive. Some USB 2.5"
    drives come with a "Y" cable, or with two USB cables, one with a barrel
    connector on the end. Those are powering schemes, that "steal" power from
    two USB ports. Since one fuse powers both connectors in a USB stack,
    the stealing doesn't help that much with an Asus motherboard. It's already
    being generous with the power. You would need to connect the "dual cable"
    to one connector on USB78 and one connector on USB910, to really
    start stealing a lot of power.

    +5VSB ----- 1.1 Amp fuse -----+------x port <------------ Max power to
    | +--- greedy 2.5"
    +------x port | bus powered
    | device
    "USB910" |
    +5VSB ----- 1.1 Amp fuse -----+------x port <--------+
    +------x port

    Firewire supports bus powering as well. Firewire has some kind of current
    limit, that the pins are rated for. Generally, it isn't recommended to
    run 3.5" drives from Firewire bus power, but it's been done. Some
    Apple compatible products, used the "capacitor bank" approach to
    storing up enough Firewire Vbus to spin up a 3.5" hard drive. If
    you're smart, you'd buy a Firewire enclosure with its own AC (wall)
    power source, to avoid doing that.

    Firewire should have no problem providing power for a 2.5" drive.
    In that case, no adapter would be needed, and no "jumping thru hoops"
    is required. It's the 3.5" drive that needs more power. A Firewire
    enclosure with a 2.5" drive inside, converts VBus (+12V or higher)
    into +5V internally, via a switching regulator.

    You will likely find a Polyfuse next to the IE1394_2 header on your
    motherboard, and by reading the value off the top of that fuse,
    you'll get some idea what safe limit Asus sets on providing
    Firewire bus power. Firewire bus power usually involves the use
    of diodes, to prevent "backflow" of bus power (something at
    least a few USB implementations apparently lack, and I've read
    a few reports of USB hubs that violate the rules on backflow).

    IBM PC implementations of Firewire, derive bus power from the +12V rail.
    The Firewire spec, allows higher voltages to be used, but normal power
    supplies don't have such a rail. Apple has built some products, with
    an additional higher voltage output, which they might use to be able to
    provide more V*I=watts to a Firewire electrical load. But when a Firewire
    peripheral is used on an IBM PC, about all they can rely on is +12V.

    1) If connecting a 2.5" drive to the computer, connect one drive per
    USB stack. If you connect two 2.5" USB drives to the same USB pair,
    one or both might not "appear" in the OS. It means they failed to
    spin up.

    2) If connecting a 2.5" drive to USB78 or USB910 headers, connect one
    drive per 2x5. If you connect two 2.5" drives to USB78 for example,
    the combined spinup current may open the Polyfuse.

    3) If using the "dual cable to USB 2.5" drive" approach, to solve a powering
    problem, run one USB connector to USB78, and one USB connector to USB910.
    That will maximize the available power, and hopefully avoid any issues
    with the Polyfuses. Wiring a "dual cable to drive" that way, could provide
    up to 5V @ 2A to the USB drive. (Eventually, the ATX supply is the next
    limitation to current flow, as the USB bus power now comes from +5VSB.)
    Dual power cabling on 2.5" drives, is only really needed if you can't
    get a response from the drive, or the drive craps out in the middle of
    a transfer.

    For 3.5" drives, normally they're powered from a wall adapter. In which
    case, you can plug them in anywhere. My Firewire enclosure is AC powered
    from the wall, so it presents no bus power loading. My 3.5" USB enclosure
    is powered from an AC wall adapter as well.

    It's only the 2.5" drives, that try to derive operating power from
    the bus connection. And in cases where the electrical load is not
    met, you simply "can't see the drive". Solving the powering issue,
    makes the drive visible in your OS. A "Y cable" or "dual cable with
    barrel connector for power" are intended to solve inadequate
    bus powering situations for 2.5" drives. Very few 2.5" devices come
    with their own wall adapter.

    Paul, May 6, 2011
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  3. me

    me Guest

    Thanks for the reply Paul,

    Both 3.5 inch drives are in Thermaltake A2396 external cases. One drive is
    a WD 800gb green drive and the other is a WD 1T Green Drive. It seems that
    most of the time whhen I tuen them both on at the same time after the
    system is booted, one or both may not show in explorer. I have an
    assortment of USB cables and have tried every one and seems to make no
    difference. I have both of the connected to the usb/1394 combo header
    plugged into the blue and red connectors. I also have another two port usb
    header plugged into the other blue connector and when I try it I get the
    same results. Should both be plugged into the same one or should I plug
    one into each one, or does it matter?

    I seem to remember that if both blue connecotrs are used at the same time
    it can cause a problem with another device on the board but cannot recall
    what the symptoms are as it's been a long time. BTW, I have tried
    plugging both drives into the ports on the back of the board with same
    results. Does the drive need to be powered up before booting if I want to
    connect one to the esata port? Both enclosures have a swirch for
    usb/esata. Any help would be appreciated, thank you.
    me, May 6, 2011
  4. me

    me Guest

    I forgot to mention that I am not using the 1394 port on the external
    header and could disable it in the bios if that matters any.
    me, May 6, 2011
  5. me

    Paul Guest

    In the picture of your product on Newegg, I see an AC adapter is provided.
    And that is where the majority of power for the drive will be coming from.


    The reviews in the "Feedback" column, note a few issues. Those issues
    might be power related. One problem with a lot of electronics these
    days, is cheap adapters. That's why reviewing the Feedback postings
    is so important - to spot substandard components.


    "Died after approximately 8 months of use. It appears to be a problem with
    the power connector/power supply. The drive repeatedly spins up and down
    when connected to the enclosure."

    Perhaps viewing any LEDs on the unit, would give some indication of whether
    it has a power problem (flickering, blinking, etc).


    You can see the green Polyfuses, next to the blue 2x5 headers on the motherboard
    (to the left of them in this picture).


    The six black colored USB connectors in this picture, should have a Polyfuse
    per two connectors. And those Polyfuses should be relatively near the stacks,
    on the motherboard.



    I see your 2x5 USB to slot adapter, in this picture. When you connect the
    blue connector on this adapter, are you able to test each USB connector
    individually ? Can you connect a USB flash stick and test each port, of
    the two ports on the slot adapter ?


    And once you pass that test, can you connect *two* USB flash sticks ? Are
    both visible ? This would be a test case, of a device that cannot cause
    any "power backfeed" type issues.

    If you can pass that test, then perhaps the Thermaltake A2396 is pumping
    power backwards, into the PC, via the USB bus power... That's about
    all I can think of.

    I've heard of cases, where you can only connect *one* of a product,
    or there will be trouble. But I thought that was a particular NAS
    box that did that. With USB, you'd think if each had a unique serial
    number, or no serial number at all, you could connect multiple of them.

    You might also consider using something like UVCView, or even Device Manager,
    to see if both of them are present or not. UVCView would show you
    whether the VID/PID config data is available to the computer or not.
    If both of them reported exactly the same information, perhaps Windows
    Plug and Play has a problem with it, and then the second one can't appear
    in Device Manager. In which case, you'd want to use UVCView to verify.

    UVCView and UVCView2 are Microsoft programs, which they've removed for
    easy download. There are ways to get it - a recipe for getting the
    latest one is here.


    Basically, you'd be looking for proof, that the front end of each
    ThermalTake adapter, can be seen. There would be two items, with the
    same idVendor (VID) and idProduct (PID).


    Paul, May 6, 2011
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