Motherboard killing PSU?

Discussion in 'PC Hardware' started by hdshank, Jan 1, 2018.

  1. hdshank

    hdshank MDL Novice

    Jun 21, 2015
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    My PSU went belly-up and I had another available. I put it in, turned everything back on, and within a second or two the second PSU was also dead.

    I received a replacement in a few days and replaced the latest dead one. The same thing happened - dead within a second or two.

    Yes, I shorted 14 & 15 on all of them - no response. But when I shorted the third PSU before installing it, the fan started spinning. After the installation - dead.

    What the devil is going on here? Anybody?
     
  2. TigTex

    TigTex MDL Member

    Oct 5, 2009
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    You might have a short circuit on your motherboard (bad VRM, damaged capacitor, etc) and the PSUs that you are using don't have overcurrent/short circuit protection and they die on you. Make sure that you buy a good quality PSU and replace or service that motherboard before you do more damage, like a dead CPU if the problem is the motherboard VRM circuit.
     
  3. hdshank

    hdshank MDL Novice

    Jun 21, 2015
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    Thanks for such a prompt reply, one which raises a couple more questions for you, if you have the time and inclination.

    1) My MB (currently out to Gigabyte for analysis) is an expensive Gigabyte board, only about 6 months old. Shouldn't I be able to assume Gigabyte would build it with all necessary protections?

    Gigabyte emailed me to say that their analysis showed a bad CPU socket. I have yet to decide whether to have it fixed, or to buy a new MB.

    How/why would the socket go bad all of a sudden. It just sits there under a bunch of other immovable hardware.

    2) My PSUs were by XFX and EVGA, both reputable manufacturers, I assume. Wouldn't they have protections built in also?

    Now I'm scared to do anything: is the MB going to kill another PSU? Is the PSU going to kill the MB? I don't know which way to go. Any advice would be greatly appreciated.
     
  4. Joe C

    Joe C MDL Guru

    Jan 12, 2012
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    1) Motherboard manufactures do not take responsibility for the fail of your power supply if it does not have over load protection.
    Gigabyte stated your board has a bad socket, You'll need to get it fixed, I would think they'll give you another board, possibly not new.
    Get another PSU, An EVGA, Corsair or Seasonic. (personally) I'm Not sure about XFX PSU's.
    When you get your board back, place it on a cardboard box, install memory, cpu/heatsink/fan. Also a GPU if necessary and connect the new power supply to it while it's out of the case to see if it'll post. If you have no issues then carefully inspect your case to see if something on it is shorting out the board before you re-install your mother board
     
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  5. hdshank

    hdshank MDL Novice

    Jun 21, 2015
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    Thanks, Joe C, I'll do that. But I still don't understand why any of that would go bad when there are no moving parts. What would cause something to short when there's no friction, nothing pulling or pushing or twisting anything.

    I can understand if the CPU or other parts on the MB quit working due to heat, but short out? That doesn't make sense to me when the computer has been sitting there for 6 months, unchanged, not overclocked at all, with quality standard components, 4 fans blowing, a large CPU cooler.

    All this happened right before Xmas, so I haven't heard any more from Gigabyte. Maybe I can get hold of them tomorrow and they can explain better about what they found on the MB. I like the idea of asking for a replacement, but they've already told me what it would cost to fix it, so I don't know if they'll go for it. I'll try, anyway.

    Mucho thanks again!
     
  6. Joe C

    Joe C MDL Guru

    Jan 12, 2012
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    Not an electronics person, but I know there's current flow through capacitors, resistors and transistors. When you got a boat load of that on a main board... I reckon stuff happens. Not physical like moving mechanical things but more like moving electrons through things
     
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  7. hdshank

    hdshank MDL Novice

    Jun 21, 2015
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    Well, if there's one thing I have learned over the years when it comes to computers, as you say, stuff happens, and often you have no idea why, nor have any idea why things just start working again.

    In the early years, computers were kind of like an old 1964 Chevy Nova I had: you open the hood and it looks so empty in there you'd think someone forgot to put the engine in. Now when you open the hood, there's so much stuff in there, you can't even find the engine.

    Nowadays, there's so much stuff on the MB that who knows what's going on. I'm not sure the system designers even know for sure. Figuring out what goes wrong is almost impossible sometimes. I guess this is one of those times.

    Thanks for your help. I guess I'll see about putting my box back together with new components. Using a Surface Pro 3 instead of a Core I-7 with a big screen and terabytes of storage just ain't cutting it.
     
  8. sebus

    sebus MDL Guru

    Jul 23, 2008
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    But you CAN use i7 Surface Pro with two massive monitors & **** lots of storage via Thunderbolt...
     
  9. mxman2k

    mxman2k MDL Developer

    Jun 20, 2007
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    WIth modern PSU's (of decent make) they have short circuit/over-under volt protection circuits. Which when triggered due to a fault, keep the PSU in OFF/Fault mode while mains voltage is still present. To reset remove mains lead and wait a minute or two, if the circuit is a good one it will then switch back to ON/Ready mode when retried. If the circuit used is a simple one then a tiny 'fuse' will blow and the psu is kaput.

    With motherboards these days like most electronics that are 'flow-soldered' and mass produced, because lead was removed from most solders this can cause a 'bad' joint, which may not show up for a while.

    I have had a few newer motherboards work for a while maybe a year or two then just give up, no visible signs of caps gone bad etc, but on very close inspection saw a few soldering problems.

    One MSI board i had failed for same reason you had, a 'bad' cpu socket, in my case the joint(s) become un-soldered due to heat, but not short anything.

    The cpu cooler cools the top part of the cpu but not the underside of the board which still can get quite hot, this can lead to the solder to become detached, due to heat/cold cycles flexing the board over time.

    MSI replaced my board, as a repair was not an option, probably because of the work involved manually re-soldering all those tiny connections!

    Hopefully you will get a replacement board - just hope they test it before dispatch!
     
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  10. hdshank

    hdshank MDL Novice

    Jun 21, 2015
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    I hope you won't mind if I ask you a couple of questions about your response.

    Can you explain a bit further what this means: "To reset remove mains lead and wait a minute or two, if the circuit is a good one it will then switch back to ON/Ready mode when retried." What/where are the "mains" leads? Do you mean leads on the PSU, or on the MB? I'm a real neophyte when it comes to basic electrical stuff. All I ever learned about electricity is that if you're going to fool with it, turn off the circuit at the breaker box ( and hope when you switch it back on everything works and your house doesn't burn down) ! :)
     
  11. hdshank

    hdshank MDL Novice

    Jun 21, 2015
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    Thanks for the info about the Thunderbolt. I'd heard the term, but didn't know what it was. I think I'll get one, whether I have a big box computer or any other kind.
     
  12. mxman2k

    mxman2k MDL Developer

    Jun 20, 2007
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    I meant the power lead from the mains socket to the psu. Or even turning off the switch on the back of the PSU close to the mains input (if one is present).

    Most decent PSU's (all 80+ rated type for sure) will have that short/over/under circuitry which if something causes the circuit to go into 'fault' mode the switch mode power supply would 'trip' and remove all output voltages as a safety measure and would stay in that mode until the input power (mains) is removed.

    After a minute or two with the main disconnected, the decent PSU's would 'reset' to normal/ready mode. This cycle would continue until the short/fault is rectified.
     
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