GA-78LMT-USB3, no USB3

Discussion in 'Gigabyte' started by John, Mar 31, 2014.

  1. John

    John Guest

    A friend has a system based on a GA-78LMT-USB3 (mobo rev 5.0) and
    can't get any of his USB3 ports to work. The USB2s are fine, but the
    USB3s, both on the front panel and the back panel, are not.

    The ports have power -- when an MP3 player is plugged in, it charges.
    But there is no data connectivity. The system (Windows 7, 64-bit)
    can't see any device that he plugs in.

    I checked the BIOS settings and USB3 is enabled. I tried to reinstall
    the USB3 driver (D/L'd from the Gigabyte site) and the installation
    failed, saying it could not find the hardware.

    I'm thinking he has a hardware problem and he's going to have to
    return the box and probably have the mobo replaced. But before he
    does that, is there anything else I can try?

    Thanks for any suggestions

    Reply-to address is real

    John, Mar 31, 2014
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  2. John

    Paul Guest

    Pop in a Linux LiveCD, and see if the USB3 chip is detected.
    Linux has the "dmesg" scrolling log file, which is freshly created
    on boot. The buffer is only so big, so if enough events happen,
    some of the more interesting messages could be lost. Typing
    "demsg" in a Terminal window, dumps the log.

    Linux also has things like "hwinfo" to display detected hardware.

    Windows, there are a number of utilities you could use. This is an
    old utility, but I happen to like it. Even if at this date, a
    number of things will show up as "unknown". You still have the
    VEN/DEV or VID/PID numbers to use from the screen of this tool.

    "EVEREST Free Edition 2.20"

    For things not automatically identified, there is a PCI database,
    filed by VEN and DEV numbers.

    There is also a USB database, for USB peripherals connected
    to USB ports. These are filed by VID and PID numbers.


    This is a simplified view of a peripheral chip.

    Bus ---- Logic --------- I/O Pad --->
    block Signal Driver (D+, D-)

    If static electricity hits the signal wire with the arrow on it,
    that can blow out the hardware signal driver. The result is,
    Windows continue to detect the logic block and tell you
    everything is fine. But no amount of plugging and unplugging
    peripherals elicits a response. It's like the chip is "deaf".

    There is another reason for that failure to occur. Sometimes,
    popular brand computer cases, the front panel cables are *miswired*.
    This can cause the port to fail.

    If you suspected that in this particular situation, you might
    refuse to connect the front panel wiring when the new motherboard
    comes back. I use a multimeter to "buzz" the wiring and ensure
    the right things are connected on either end of the cable.
    If you've experienced a peripheral failure, on a peripheral with
    front panel wiring, don't hook up the wiring again! That's the
    simplest prevention. I have two Antec cases with wiring errors,
    but fortunately, they never hooked VCC to the wrong pin. If
    I'd gone ahead and used the front cables, the port would have
    refused to work. My back ports work, so I know my chip is not

    Another form of failure, is when the bond wire for VCC or GND
    on the driver pad, burns out. This can be caused by latchup,
    which is caused by static discharge. An example of the bond
    wire blowing, is shown here. The top of the IC in question
    (Southbridge) has a burn mark.

    (I'm surprised this site still works!)

    The logic block itself, hardly ever fails.

    The chip select to the logic block, can be
    blocked by the BIOS. So disabling the chip in the BIOS,
    can make the logic block "disappear" and refuse
    to be detected. I'm not really sure of all the
    ways that's implemented now, so I can't help with
    theories at that level. PCI Express doesn't work
    quite the same way as PCI, and I don't know the
    ways that are guaranteed, or most of the time work,
    to disable chip response. PCI Express is a hub bus, and
    disabling an "arm" of the star wiring, could stop a chip
    from working. Even disabling a clock signal for the chip
    could be used to kill it, but that is not normally recommended
    as a hardware control method (I've had hardware burn by doing
    that :) It seemed funny at the time).

    Use the detection methods first (like Everest),
    before sending the motherboard back.

    Another thing you could try, is to remove all power
    from the computer. Do the "clear CMOS" thing, which
    causes all the BIOS settings to be reset. You could
    even remove the CMOS battery, to help clear the
    CMOS settings.

    Sometimes, unexplained behavior is actually caused by a
    CMOS variable you cannot observe. Removing PC power can
    help with certain kinds of hardware failures, while removing
    all power (unplug) and pop out the CMOS battery, helps with
    errant settings. You should record (either with a camera or
    write them down), all the BIOS screen settings before you do
    this, so you can put them back later after clearing the CMOS.

    Clearing the CMOS should only be done, with the computer
    unplugged, as many motherboards have a purposeful design
    flaw, where a diode on the motherboard gets burned if you
    Clear CMOS with the power still on. Unplugging is a nice
    safe policy for this.

    If I knew of a web forum for the GA-78LMT-USB3, I'd go research it.
    You could try Newegg reviews or Amazon reviews, to see if
    this problem is a common one. I looked at a few reviews, and
    blown USB3 isn't standing out there.

    The motherboard manual says the USB3 chip is VIA VL805 quad port USB3.
    The quad port means two USB3 on the back panel, as well as a dual
    connector for front panel wiring (19 pin F_USB30 connector). The missing
    pin is for keying, so the connector goes in the right way. Since the
    pinout isn't particularly symmetric, maybe putting the connector in
    the wrong way will blow it ? You would need to take the single sheet
    of paper for the computer case documentation, to see if everything
    matches. And check whether the computer case cable has a keying tab
    to mate with the place for a tab on the motherboard connector. If no
    keying mechanism is evident (computer case cable isn't keyed), it's up
    to the user to put it in the right way :-( Now you know why the replacement
    motherboard, you want to be careful with that F_USB30 thing (if it isn't
    keyed to make pin 1 go to pin 1).

    Paul, Mar 31, 2014
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  3. John

    Paul Guest

    You could verify the state of the drivers with Device Manager.

    Paul, Apr 1, 2014
  4. John

    John Guest

    I've installed USB3 drivers on another Win7 system (the one I'm using
    now) with nothing plugged in. The driver is on the mobo
    driver/utility disk that typically gets installed right after Windows.
    Device Manager shows USB3 root hubs and host controllers installed and
    working properly.

    In my friend's case, Device Manager does not show any USB3 devices,
    and the driver would not install because it couldn't find the

    Reply-to address is real

    John, Apr 3, 2014
  5. John

    John Guest

    Thanks for the detailed explanation and advice. My friend didn't want
    to go through all the steps; he's kinda convinced (as am I and as is
    the tech support guy at the company he bought from) that it's a case
    of dead hardware.

    He was ready to RMA the box but they offered instead to send him a new
    mobo, which would be faster and cheaper than shipping the whole
    computer back. I told him to go ahead and I'll give him a hand
    swapping the board.

    I'm pretty sure that we should be able to do this without reinstalling
    any software. That is, we can shut it down, swap the board, then turn
    it on and Windows and all its drivers and such will never know the
    difference and will just boot up and run.

    Am I right about this? Are there any gotchas that I have to worry
    about? (I'm assuming they will send a same-rev board, which I'll
    check before we start.)

    Reply-to address is real

    John, Apr 3, 2014
  6. John

    Paul Guest

    Windows activation keeps track of hardware changes. When you change
    the motherboard, it changes the NIC MAC address.

    This ancient article describes how it works.

    It would really depend on how many perceived changes
    have happened to date, as to what it would think
    about the new motherboard. If only the motherboard NIC MAC
    changed, maybe it would simply work :)

    Paul, Apr 3, 2014
  7. John

    John Guest

    I wasn't thinking of that. Yes, I've heard a variety of stories over
    the years about how Windows' registration algorithms work and I
    suspect none of them is exactly right and the truth is a
    closely-guarded secret like the formula for Coca-Cola. :)

    But at worst that should take a phone call to straighten out,
    especially since he has correspondence from the vendor showing that
    the board was swapped because it was defective.

    And I'm expecting that a Windows re-install won't be necessary since
    the board is identical (except for the MAC address and the board's S/N
    if that's part of the equation) so all the drivers and settings are
    already in place. (Hmm .. note to self: check and record CMOS
    settings before removing old board!)

    Reply-to address is real

    John, Apr 4, 2014
  8. John

    john Guest

    To bring the story to an end:

    He accepted the offer to RMA the mobo instead of the whole box and
    today we swapped out the board.

    All is well. The system booted Windows and everything works just fine
    including the USB3 ports. Nothing needed to be reinstalled and no
    authentication was required.

    (Windows did notice that something had changed. There was a dialog
    box that I've never seen before showing that it was checking and/or
    reinstalling drivers. But no intervention was needed, it all just

    Thanks for all the help.

    -- john
    Reply-to address is real
    john, Apr 14, 2014
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