new system bootup woes

Discussion in 'PC Hardware' started by Adam, Dec 17, 2014.

  1. Adam

    Adam Guest

    Host OS: Ubuntu Desktop 12.04 LTS
    Motherboard: ASUS Sabertooth 990FX AM3+ AMD SATA 6Gb/s USB 3.0 ATX
    Computer Case: Antec Three Hundred ATX Mid Tower
    Power Supply: OCZ ModXStream Pro 600W Modular

    I am having trouble with power to brand new system.

    After talking with OCZ tech support and doing a simple test,
    we were able to get the PS fan to spin-up. OCZ Tech support concludes that
    this is a strong indication that the PS is functional.

    Next, I suspect that the Antec case's I/O panel wiring to mobo pins may
    be the culprit. The wiring seems fine to me but still no power.
    Maybe a loose connection? How to make a stronger connection?

    Any ideas?
    Adam, Dec 17, 2014
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  2. If the system powers up to where the power supply fan runs then start
    looking a the motherboard. Any post codes? Indicator lights on
    motherboard? Reseat RAM. Check CPU, remove all cards except video (if
    not using onboard) and see if it posts then.
    Jonathan N. Little, Dec 17, 2014
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  3. Adam

    mike Guest

    What does your voltmeter say?
    mike, Dec 17, 2014
  4. Adam

    Adam Guest

    Oh boy, that's new to me. I'll see if I can find any "how to" links on
    troubleshooting with a voltmeter.
    Adam, Dec 17, 2014
  5. Adam

    VanguardLH Guest

    Oh, that "trouble" since there can only be one. It's a secret trouble.

    Doesn't sound like an OS problem since the unidentified "trouble" is
    probably to get it powered on which is before the OS is even loaded by
    the BIOS.
    Not really. PSUs that have crapped out by not being able to handle the
    load can still spin their own fan(s).

    Did you notice if the CPU's fan is spinning, too?

    If using a mechanical HDD, do you hear it spin up on power on? How many
    HDDs are connected? Tried with just one?

    Did you populate all mobo RAM slots with matched memory modules? Or did
    you mix them? They have a warning on their spec page saying "AMD 100
    series CPUs support up to DDR3 1066MHz. With ASUS design, this
    motherboard can support up to DDR3 1333MHz."

    Did you disconnect all USB devices and then retest that the "trouble"
    went away?
    Do you have a separate daughtercard for the video? Or are you using
    onboard video? If a daughtercard, did you remember to hook up the PSU
    4-pin connector to the video card's extra power connector?

    The mobo has a 24-pin power connector. The PSU may come with a 20+4
    connector: 20 pins in one connector with an ancilliary 4-pin connector
    you add (slide on or rotate and snap into place). Did you use 24 pins
    from the PSU to the 24-pin power connector on the mobo? Did you connect
    an 8-pin connector from the PSU to the 8-pin power connector on the
    mobo? The manual says "Do not forget to connect the 4-pin/8-pin EATX12
    V power plug; otherwise, the system will not boot."

    With modular PSUs, sometimes users hook up only the minimal connects and
    omit some crucial ones.

    Do you have 2 high-end PCI-e x16 video cards? If so, Asus recommends a
    1000W PSU.
    VanguardLH, Dec 17, 2014
  6. Adam

    Paul Guest

    Now you understand why I "bench test" on the kitchen table first,
    before putting the system in the computer case.

    You don't absolutely need *any* wiring to the front panel at all,
    for a bench test. But what I do instead, is keep a push button switch
    with two connector pins on the end, which slide over the PWR and Ground
    pin pair. That's for turning the system on. I can also slip a screwdriver
    tip between those two pins, to bridge them and start the system. That
    requires a good deal of care and dexterity, and is only
    practical when the motherboard is sitting on the kitchen table.

    On the picture there, you can see that header has a "dangerous pair"
    in the SPKR pin area. Don't bridge that +5V pin if you can possibly
    manage it, to any adjacent Ground pins. It's another one of those
    situations where there may be no protective fuse in the path.


    In the past, some Antecs have had wiring errors in USB or Firewire
    cables (that's a 2x5 on the motherboard end, leading to a front
    panel mounted connector). So I would not hook up the front panel I/O
    wiring at all. On a couple Antec cases here (I have at least three
    of them), I use the multimeter, set to ohms range, to verify the cable
    wiring is correct. It's just easier to *not* use Antec front wiring, than
    be bothered to do that. None of my Antec front USB ports are hooked up,
    for this reason. I'm too lazy to correct the errors by moving the
    pins around in the 2x5 end.


    I take it, OCZ had you do the "unconnected supply" test ?

    For that one, you bridge PS_ON# to GND on the ATX cable.

    Bringing the logic level low on PS_ON# is what makes
    the supply fan spin, and the main supply section to function.
    On page 37 here, that would be the green PS_ON# wire, to an
    adjacent black GND wire. Some people recommend connecting
    a dummy load to the supply, in the form of an old (scratch)
    hard drive or something that draws a similar small amount
    of power.


    This is a simplified model of the ATX supply. There are two
    power generation circuits, and +5VSB is separate from the rest.

    AC Input ------+--- +5VSB circuit
    +--- +3.3/5.0/12V main section

    When you switch the supply on at the back, the +5VSB starts to
    produce power immediately. The fan will not be spinning at
    this point. The +5VSB provides 2 to 3 amps max, and is
    used as a supervisory voltage, amongst other uses. The
    ATX power supply is convection cooled at this point, when
    removing heat from the +5VSB circuit. Due to the modest
    capacity of the +5VSB, it doesn't get too warm.

    When the ATX power supply main cable has PS_ON# and GND
    brought together, that grounds the pullup resistor on
    PS_ON#. Normally, with a voltmeter, you'd see 5 volts
    level on PS_ON#, and it's when that level is grounded
    that the supply runs. The fan begins to spin, and the
    main voltages begin to be produced. The motherboard
    would be starting to POST at this point. The case
    fans would be spinning.

    If you attempt to start an ATX supply, and you see
    the PSU fan "twitch" about a half inch of rotation,
    that means the supply tried to start, but encountered
    a serious short circuit (current overload) on the outputs.
    To protect against burning any cables, the ATX supply
    has latched off. Normally, you'd need to switch off at
    the back, wait 30 seconds, switch on again, to make
    another attempt to start the system. The reason the
    supply "twitches", is the overcurrent is disabled
    for the first 35 milliseconds, until the PSU has had
    a chance to charge the output capacitors, and that
    allows the fans to receive current for 35 milliseconds.
    The fan blades can only "twitch" in such a short time
    frame. If the "serious short" is present, when the
    overcurrent detection is enabled at 35 milliseconds,
    the power supply immediately shuts off the main section.

    (The reason you wait 30 seconds, is to give any inrush
    limiter time to cool off.)

    In this diagram, the +5VSB is used to power the control
    circuits. The motherboard logic "latches" the momentary
    logic low level from the front panel switch, and drives
    out a "steady" 0.0V level on PSON#. And that's what is
    used to control the ATX supply.

    +5VSB (0.0V level +5VSB
    | means "run please") |
    Pullup \_ Pullup
    Resistor \ Resistor
    | PS_ON# |
    PWR X----+---- Motherboard ---- Open -------------------+- ... control
    / logic Collector (to of main
    | GND X----+ Driver ATX + PSU
    | | supply) | section
    (Front GND GND
    Switch - normally open, momentarily close to operate)

    By removing any USB panel header or Firewire panel header wiring
    from the front panel to the motherboard, you're removing
    a possible place for electrical shorts to happen. Wiring
    up the PWR button from the front of the case (two wire twisted
    pair labeled PWR and GND), gives you enough control to turn
    the system on and off.


    On an Asus motherboard, there is a green LED which is wired
    in such a way as to monitor for +5VSB. If the ATX PSU is supplying
    +5VSB, and the main PSU cable is wired up, the green LED should
    be glowing. And the LED should not flicker. It should be
    a solid level for the entire time that the switch on the
    back of the ATX supply is in the ON position. Asus provides
    the LED, to tell you when it is safe to work inside the PC.
    The LED must be completely extinguished, before you
    work on RAM DIMMs or pull PCI Express cards, that
    sort of thing. It takes up to 30 seconds for +5VSB to
    drain, after the ATX PSU is switched off.

    Paul, Dec 17, 2014
  7. OCZ tech support is full of it because the only thing a spinning
    fan indicates for sure is that the +12V rail is putting out at
    least 5V to 6V, the minimum voltage that most 12V fans need to
    spin up. It's possible one of the other positive voltage rails
    isn't putting out anything, and you typically need all 4 positive
    voltage rails working right for the computer to run, especially
    the +5Vstandby line, which is separate from the main +5V. A cheap
    digital multimeter is great for diagnosing PSU problems and a lot
    of other things, unlike a PSU tester (the ones without digital
    readouts but just LEDs are useless). Can you borrow a power supply?

    Over the past couple of years, I've seen several brand new power
    supplies not work with motherboards until I plugged and unplugged
    their connectors several times, maybe due to oxidation or a coating
    on the contacts so try this, 5-10 times.

    Have you tried turning on the motherboard directly through the 2
    power-on header pins on the motherboard? Do this with the front
    panel cables disconnected. If that works, then you know something
    is wrong with the cable wiring.

    See that the memory and any plug-in cards are seated correctly in
    their sockets. Also test with just one memory DIMM installed
    (generally it's better to first test a system with just enough
    hardware installed to let you see something on the screen -- makes
    it easier to pinpoint the bad hardware).

    Do your DIMMs have tall heatsinks that may be pressing against the
    CPU's heatsink? That can prevent computer operation. Another
    thing to check is the CPU heatsink because if it's not making firm
    contact, the motherboard will probably turn off, but usually it
    will start for a second. Sometimes 1 of the 4 CPU heatsink mounting
    screws or pins is loose. And some heatsinks have terrible mounting
    hardware on the bottom of the motherboard that can make it easy
    to create a short.

    Sometimes the motherboard shorts to the case, usually at one of
    the mounting holes, a poorly supported corner, or where there's
    an extra brass mounting post underneath that doesn't line up with
    any of the holes in the motherboard. A brass post like that can
    short out traces or even crush tiny surface mount components and
    ruin the motherboard.

    What kind of anti-static precautions did you take? Did you do
    anything foolish, like wear shoes, socks, or long sleeves?
    larrymoencurly, Dec 17, 2014
  8. Adam

    Paul Guest

    When debugging a power problem, at system startup
    the components don't draw "max power". Even a modest
    power supply, mistakenly connected to a high power system load,
    should get you to the BIOS screen.

    Whereas at one time, video cards had high idle current draw,
    they've improved a lot. And even a gamer card can run cool
    when it is idle. If you're using older high end video cards,
    their power can be a bit obnoxious at idle.


    Startup condition (T=0, BIOS screen time etc...) :

    Video card - min power, low clock, 10W each on modern cards
    Processor - likely to be using one core
    Disk drive - spin-up current of 12V @ 3A for first ten seconds


    Booted and idle in desktop (maybe 150W max system-wide):

    Video card - min power, low clock, 10W each on modern cards
    Processor - likely to be using approximately one core (12V @ 1.1A typ)
    Disk drive - motor current stable at 12V @ 0.6A or less


    Booted and playing 3D game, tainted driver, SLI or Crossfire enabled:

    Video card - 3D clock rate, gaming power level (200W, high end card)
    Processor - likely to be using multiple cores (draws estimated TDP power)
    Disk drive - motor current stable at 12V @ 0.6A or less

    If the computer was unstable when 3D gaming, that might be
    a sign the supply size is not correct for the load.

    Asus offers a PSU calculator, but the numbers are too high.
    For example, a system with no video card, was rated "350W".!psu-calculator/c1ig3

    This one was a bit crazy at one time, but they've refined this
    since then. At one time, some DIMMs were rated at 25W each,
    whereas you can use Kingston datasheets to get 2-3W estimates
    for each. So when they say "most trusted", I really
    prefer the sites to display their estimate for each
    component for all to see.

    The "most trusted" power estimator, was shut down years ago.
    A shame really. It listed the power number it used for
    each component, so you could judge for yourself how
    realistic the estimate would be. For example, it would
    say my video card was 35W, and if I got out my clamp-on
    DC ammeter and checked, it was pretty close. That site had
    obtained power measurements for a number of video cards,
    from somewhere. So it wasn't using the imaginative numbers
    provided by the manufacturers either. The video card
    power numbers were "xbitlabs" quality (but predated the
    existence of Xbitlabs). And that made it a damn nice
    power calculator site. But they didn't maintain
    it, and eventually shut it down. It's a lot of work
    keeping tools like that running properly. The Asus
    one for example, should be a lot better, because they
    have the engineers and technicians to do a good job.

    Paul, Dec 17, 2014
  9. Adam

    mechanic Guest

    So send it back to the shop!
    mechanic, Dec 17, 2014
  10. Adam

    mechanic Guest

    'Avo' ?
    mechanic, Dec 17, 2014
  11. Adam

    Adam Guest

    Can't, it's a home build.
    Adam, Dec 17, 2014
  12. Adam

    Adam Guest

    Thanks, Guru Paul !!

    This is just a quick post since I will need some time to digest the info.
    Adam, Dec 17, 2014
  13. Adam

    Adam Guest

    Thanks, yep, I was looking through the mobo manual and
    there are CPU_LED, DRAM_LED/MemOK switch, VGA_LED, etc.
    Will be checking those out later.
    Adam, Dec 17, 2014
  14. You can buy a multi PS tester for PCs at Amazon or other popular
    retailer that costs about $7 to $15 and you hook you disconnected PS
    cable to it, and it gives voltages for all the ATX supply rails in the

    Easy greasy...

    Halfway down the page on the second one is a whole row of them to
    DecadentLinuxUserNumeroUno, Dec 17, 2014
  15. Also most motherboards have a speaker pins on the front panel header,
    and they include a little speaker dongle that if you connect it you can
    get post beep codes that can help.

    As someone else mentioned did the CPU fan start? LED on motherboard
    light up? HD spin up? Monitor get a signal or NO SIGNAL message?

    As I said you should try with minimal connections...remove everything
    except video and the connection to the "pwr sw" pins on the front
    header. This narrows your search.
    Jonathan N. Little, Dec 17, 2014
  16. Adam

    VanguardLH Guest

    I've seen where an underpowered or weak PSU (they get limp over time)
    won't power up a system (to the POST screen) that is minimally
    configured until the HDD is disconnected. Too much power draw on a weak
    PSU means no boot or unreliable boot despite the PSU's fans will spin.
    VanguardLH, Dec 17, 2014
  17. Adam

    VanguardLH Guest

    He did. Adam *is* the shop. Look at the specs he gave. Did that look
    like a pre-built or OEM build to you?
    VanguardLH, Dec 17, 2014
  18. Adam

    VanguardLH Guest

    If shorting the PWR pins on the onboard front-panel pins doesn't work,
    and to test the PSU is okay, bypass the onboard logic for soft power up
    of the ATX PSU. Short the PS_ON line (green wire: pin 16 on a 24 power
    connector, pin 14 on a 20-pin connector) to a ground line (black wire).
    See pinout at
    The signal floats high but the onboard logic pulls that line low to tell
    the PSU to power up. Shorting it to ground effects the same pull to low
    state. If done while the PSU is disconnected from the mobo, some PSUs
    won't power up until they sense a load, so attach an HDD.

    Front panel power switches can go bad or be defective so the PWR pin
    short is a good test; however, if that doesn't work, make sure the PSU
    will come up if its PS_ON line is pulled low.
    VanguardLH, Dec 17, 2014
  19. Adam

    Adam Guest

    Thanks, added it to my wish list just in time for Santa. :)
    Adam, Dec 17, 2014
  20. Adam

    Adam Guest

    Okay, I have disconnected the Antec case's front I/O panel USB connector.

    Yes, the "unconnected supply" test sounds like what I performed.
    Short the green wire to a black/gnd wire in order to test that
    the PS fan spins.

    Okay, the Antec case's front I/O panel USB connector is no longer connected.

    Okay, sounds like what the mobo manual calls the standby power (SB_PWR) LED,
    which lights up no problem whenever mobo is connected to PS so far.
    Adam, Dec 17, 2014
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