bios 12v rail = 9v, multimeter says 12v

Discussion in 'Troubleshooting Help' started by )(arg0n, Mar 7, 2017.

  1. )(arg0n

    )(arg0n Member

    Joined:
    Sep 24, 2006
    Messages:
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    Location:
    Melbourne
    Hey guys my server died again tonight. I posted a topic here a while ago when the quad core in it seemed to stop working, replaced it with an identical cpu and it seemed fine again for a few months.

    Had a random reboot tonight and booted itself into the bios. I thought I better have a look at the pc health screen to check volts and temp. To my surprise 3.3V was ok, no readout for 5v but 12v = 8.8v.

    I turned it off straight away suspecting bad psu. Switched in a known good one. Same issue 12v = 9v now.

    I checked with a multimeter at a few different spots on the psu and they all measured 12v while the pc was running and reporting 9v?

    Switched back to the orignial psu. Wouldn't boot again. Remove and reinsert cpu and it booted fine, third time that has happened.

    Just bin the mobo or am I missing something?

    specs:
    mobo B75m-d3h skt 1155
    cpu i5 quad 3.4ghz? (cant remember)
    psu corsair cx430
    about 8 hdds and a dvd drive
    4 sticks 16gb ram
     
  2. )(arg0n

    )(arg0n Member

    Joined:
    Sep 24, 2006
    Messages:
    440
    Location:
    Melbourne
    well it wont boot at all today even with the dual core g550 back in there which always seems to be the fail safe last time I was having issues. I'm guessing motherboard failure - specifically something to do with the voltage regulation part of things? Been playing up for a few months now but was very sparodic and hard to isolate, hopefully this is it. Thanks guys.
     
  3. shane41

    shane41 Member

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    Location:
    on the edge
    When it's running " board out of case " measure the cap 12V supply
    on the board with a multimeter.

    Those bios health checks are bulshit here on my boards " older "
    but the fluctuate greatly & the psu is trusted proven correct stable.
    _______________

    Edit. If you see a blue screen. Note the first part of it......look it up on google.
    Many of the bsod's are to do with low volts. Seen a few when clock the Haswells.
    Other one is the ram, dust in the slots. Low V as well as above. Check spec's.

    Then there's the cpu cooler. Dust again & it only has to be a small amount to overheat & play up.
     
    Last edited: Mar 8, 2017
  4. i7Baby

    i7Baby Member

    Joined:
    Jul 3, 2012
    Messages:
    289
    Corsair CX were riddled with problems early on - cheap caps causing incorrect voltages.
     
  5. )(arg0n

    )(arg0n Member

    Joined:
    Sep 24, 2006
    Messages:
    440
    Location:
    Melbourne
    Managed to get my hands on an exact identical replacement board, same revision and all. Dropped it in, set the BIOS, no worries. Voltages in the BIOS are now reporting properly. That weird screen glitch I was getting and wrote about in another thread is now gone. Im sure a mosfet feeding the cpu has died on the board somewhere, will probe around when I have time :)
     

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