Motherboard or Power Supply?

I have a machine that is suddenly somewhat dead. When I boot it, I get no output. I thought it was the motherboard at first, but now I'm not so sure.

There is no output to the monitor through the video card. The machine is not pingable. The fans in the machine do turn on (including the CPU fan)...which leads me to believe that the motherboard is not completely dead and the power supply isn't completely dead either. The LEDs on the CDROM do light up, but when I push the eject button nothing happens. Neither of the two hard drives seem to be spinning up.

I tried another good power supply and received the same result, but I'm not 100% sure I've hooked it up correctly. My motherboard has a 24 pin power connector as well as a second 4 pin connector. My backup power supply that I tried has a 20 pin power connector, as well as a 4 pin connector.

I've tried plugging the 20 pin and 4 pin power supply connectors into the 24 pin connector on the motherboard. I cannot get them to fit (the notches don't line up), which leads me to believe that I shouldn't be trying to do that anyway.

I've also tried plugging the 20 pin power supply connector into the 24 pin connector on the motherboard (leaving 4 pins open) and plugging the 4 pin power supply connector into the secondary 4 pin connector on the motherboard. This setup yield the same results as the initial power supply. Should plugging the 20 pin into the 24 pin work? (I'm not sure if the extra 4 pins are optional for something - and I don't have any SATA drives in the system) If it should have worked, then I proved that the issue is not the power supply. If it shouldn't have worked, then I have to find another power supply to test with.

My video card is a MSI NX6200TC PCI-E (It's just a basic card since I run linux on this machine) - I'm guessing it doesn't draw a lot of power.
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  1. Have you got a 4 or 8 pin connector plugged into the ATX power supply next to the CPU socket?

    If your motherboard has a 24 pin main connector, fill it with the 20 + 4 pin connector from your PSU.

    Sounds like a PSU issue as if it was just the motherboard, the hard drives and disc drives would be working as normal as they are plugged directly into the PSU. They are only attached to the motherboard via data cables and so the motherboard can't stop them from turning on.
  2. also what are your system details??
  3. nzxtlexa said:
    Have you got a 4 or 8 pin connector plugged into the ATX power supply next to the CPU socket?

    If your motherboard has a 24 pin main connector, fill it with the 20 + 4 pin connector from your PSU.

    Sounds like a PSU issue as if it was just the motherboard, the hard drives and disc drives would be working as normal as they are plugged directly into the PSU. They are only attached to the motherboard via data cables and so the motherboard can't stop them from turning on.


    It's a 4 pin.

    I tried putting the 4 and the 20 together. They just don't fit. The square and rounded-square pins just don't line up.

    The system is:
    Athlon 64 3000+
    Chaintech VNF4 Motherboard
    1GB RAM,
    2 x 250GB drives
    MSI NX6200TC Video card
  4. There are two 4-pin connectors. One is for your CPU while the other connects to the main 20-pin power. Are you sure you're not mixing them up?
  5. nzxtlexa said:
    Have you got a 4 or 8 pin connector plugged into the ATX power supply next to the CPU socket?

    If your motherboard has a 24 pin main connector, fill it with the 20 + 4 pin connector from your PSU.



    DO NOT DO THIS. sorry for shouting, but the 2x2 4 pin connector does't fit for a reason. it has 2 12v lines and 2 grounds for cpu power. this does not match with the 24 pin connector pinout:

    http://www.formfactors.org/developer%5Cspecs%5Catx2_2.pdf

    If the drives are not spinning up then they are not getting 12V, which comes directly from the psu, so looks like your psu is bad. r u sure the drives r not spinning up?

    "I've also tried plugging the 20 pin power supply connector into the 24 pin connector on the motherboard (leaving 4 pins open) and plugging the 4 pin power supply connector into the secondary 4 pin connector on the motherboard."

    This should work.
  6. leo2kp said:
    There are two 4-pin connectors. One is for your CPU while the other connects to the main 20-pin power. Are you sure you're not mixing them up?


    Actually my PSU only has one 4-pin connector.
  7. Update...I tested the machine with a brand new power supply. If I plug only the power cable into the drives and power on the computer, the drives spin up. If I plug the power and the IDE cable (going from the motherboard to the drives) the drives due not spin up. I tried this individually on 2 separate hard drives and 1 CDROM and it consistently behaved this way. The CPU fan always turned no matter what I did. The motherboard does not make any beeps or noises and there is still no video output through my video card.
  8. Well that's progress.

    I would start stripping the computer down to bare components.

    No HDD, no CDR / DVDR, only one ram module...

    Try booting the machine with no ram and video and see if it beeps. Make sure the PC speaker is plugged in too ;)

    But if the computer doesn't complain without ram or vga then the motherboard is dead.
  9. applejuice85 said:


    Try booting the machine with no ram and video and see if it beeps. Make sure the PC speaker is plugged in too ;)

    But if the computer doesn't complain without ram or vga then the motherboard is dead.


    No. Still could be cabling, PSU, or CPU also.

    http://www.tomswiki.com/page/Troubleshooting+a+New+Build
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