Is this motherboard shot?

Discussion in 'Motherboards' started by killem2, Feb 16, 2010.

  1. killem2

    killem2 Coastermaker

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    I came over to my friends house to help him with his pc, and he was getting a no signal error from his video card. So i tried resetting the cmos, and blowing out the ports and such, same thing.

    I took the cable and tried each port, same thing. I took the cable to my pc, worked fine. I took the cable from my monitor to his pc, same thing.

    So i took my hd5850 out, put it in his PC, same thing no signal.

    i put his 9600gt into my pc, worked great out of ONE port.

    he also complained of his keyboard and mouse (both ps2 connections) going out every once and a while.

    Also, his on board video would give no signal as well, vga, and dvi ports.

    New motherboard time?
     
  2. Rob Williams

    Rob Williams Editor-in-Chief Staff Member Moderator

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    Could it be his monitor, then? I have found in the past, that I'd receive a "No Signal" error even if the motherboard was dead, because the port would still be powered. It might be worth trying to hook up another PC to the monitor first, or another device (like a console) to rule out that it could be the monitor or not.

    If it's not the monitor, it could be the motherboard, but it's hard to say. Even a RAM stick that's gone bad could screw up the boot process. I'd recommend taking out all the RAM, and using just one stick in the primary DIMM slot, one at a time, to see if it boots. If a RAM stick goes bad, the "No Signal" error can be common.
     
  3. killem2

    killem2 Coastermaker

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    At first I thought it was, but we did hook up his monitor to my pc with my 5850 and it worked fine, and we hooked up his 9600 gt in MY pc, and it also worked fine.
     
  4. Rob Williams

    Rob Williams Editor-in-Chief Staff Member Moderator

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    I'd still try different RAM, just to see. If it's not that, then it does indeed seem that the motherboard has been killed off.
     
  5. b1lk1

    b1lk1 Tech Monkey

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    Agreed, ram is always the first thing to die for the most part.
     
  6. 2Tired2Tango

    2Tired2Tango Tech Monkey

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    It could also be power supply. If the 5 volt suppy is flakey it will cause all kinds of screwball problems.

    Before you do anything else, get some voltage readings from the supply and see if they're OK... Know anybody that has a voltmeter and knows what to look for?

    If the voltages are all wonkey a bad power supply could damage any replacement parts you put into the system.

    If it was just RAM or video, I'd expect to hear a beep code from the in-case speaker.

    http://www.pcguide.com/ts/x/sys/beep/index-c.html
     
    Last edited: Feb 16, 2010
  7. Rob Williams

    Rob Williams Editor-in-Chief Staff Member Moderator

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    Ahh, the joys of fiddling to figure out a tech problem... never gets old.

    Actually, it does. This problem gives me a headache just thinking about it.
     
  8. Psi*

    Psi* Tech Monkey

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    I would go along with 2Tired2Tango's thought about the power supply. And, I'll up the ante with do not keep powering the system up. My experience is that things will further degrade & both the PSU & m/b will finally & conclusively be bad.

    Only my theory, but I think certain failure modes of PSUs take out the m/b:(
     
  9. Kougar

    Kougar Techgage Staff Staff Member

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    My first thought was with 2Tired's on this one, I'd suspect the power supply first. Try to rule that out before replacing the entire motherboard, especially as if it is a bad PSU then it could potentially kill a new board.
     
  10. killem2

    killem2 Coastermaker

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    Memory seems to be a pass, I had my friend try to boot up each stick separately in each slot same issue, then the other same issue.

    U Am going back tomorrow to try my power supply to get the final verdict.
     
  11. 2Tired2Tango

    2Tired2Tango Tech Monkey

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    I trust you're not planning to hook that power supply up to anything until you get it properly tested... Seriously, you could end up killing a perfectly good motherboard!
     
  12. 2Tired2Tango

    2Tired2Tango Tech Monkey

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    You haven't lived until you see all the caps around the CPU exploded into little fuzzy balls...
    And don't even get me started about the smell.
     
  13. killem2

    killem2 Coastermaker

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    My power supply is awesome. That's the one I was going to test. If his is broken I don't want to hook it up at all.
     
  14. 2Tired2Tango

    2Tired2Tango Tech Monkey

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    Ok... one last point, and please don't take this as anything but me trying to help...

    You're got that system in a wooden case, ya?

    Did you run ground straps from the power supply case to the motherboard and your disk cage?

    A suitable ground strap would be something like 16ga lamp wire with loop ends soldered on. (crimp connections ain't gonna cut it here) You should use at least two runs, starting from a relatively large screw on the power supply case to at least one mounting bolt for your motherboard and at least 1 mounting bolt on your disk cage. Personally I would use 3... 2 on opposite sides of the motherboard and the 3rd to the disk cage.

    The problem being that metal cases provide a really really good common ground for your system that wood simply cannot.
     
  15. b1lk1

    b1lk1 Tech Monkey

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    Motherboards do not use the case as a common ground.
     
  16. 2Tired2Tango

    2Tired2Tango Tech Monkey

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    I'm sorry? You really do need to check that...

    The mounting lands are electrically connected to a ground plane inside the PCB, the screws connect the lands to a metal backplate that is connected to the metal case which is in turn connected to the power supply case through it's mounting screws, inside the supply the case, it is connected to the ground wire of the cord... Similarly the drives mount in a cage which is mounted to the same case frame as the motherboard and power supply... That is a common ground, if I ever saw one.

    Ever watched a competent tech checking voltages in a PC? Where does he put is ground clip? Yep... on the case... Why? Because it's a ground connection with resistance measured in milliohms... the most accurate "zero voltage" point in the entire system.

    Have you never wondered why they use metal cases when they could make plastic ones for a fraction of the cost?

    Really man... I know you love to disagree with me but this is getting just a tad ridiculous....
     
    Last edited: Feb 17, 2010
  17. killem2

    killem2 Coastermaker

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    I do not do this, as my psu is plugged into a correct electrical found from the outlet.
     
  18. 2Tired2Tango

    2Tired2Tango Tech Monkey

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    That's not the point.... Bringing everything to a common ground voltage is not just an electrical safety thing...

    Not to drive this too hard but...

    Ever figured out how much current your motherboard draws?

    Ohms law tells us that Current == Power / Voltage ... I = P/E ... So, applying this to just a typical 80watt CPU chip... Lets say it's running at 1.5volts... 80/1.5 == 53.3 AMPS of current... That's about the same current a typical car's headlights draw, and that's only for your CPU chip...

    Now add in the chipset, I/O cards, video, etc.... 80 amps is not uncommon and *all* of that flows through your ground wires.

    How much voltage offset will this cause?

    Well, Ohm's law also tells us that Voltage = Current X Resistance... E = I X R... We know we have at least 53.3 amps of current flowing... so lets assume the wiring from your power supply has .1 ohm of resistance... 53.3 X .1 == 5.3 volts ... OOPS... that's way more than the logic voltage on your boards...

    Yes, an extremely low resistance ground is essential in these systems...

    Ask yourself... Did you have these problems when the system was in a metal case?
     
    Last edited: Feb 17, 2010
  19. Glider

    Glider Coastermaker

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    http://www.clearpc.ca/

    The motherboard uses the BLACK wires as ground, not the case... There are contact points around the screw holes, but that is to make sure all metal around is at the same potential, not to act as a ground... If that was the case, a PSU that isn't mounted inside a case would never work, because the electrical flow is interupted, but you already knew that, right?

    Why do they put clips on the case? Because they are too lazy to actually fiddle around and get a black wire. And since everything is at the same potential, it doesn't matter...

    So, your CPU uses 1,5V, but about all the rest uses 5 or 12V, so get your facts straight... 50A of current does not do good things to the small wires of your PSU... In an house, 20A must be a 2,5mm2 wire, 32A goes through a 6mm2, 50A will be upwards of 15mm2 (can check the numbers if you want...) And that is AC, which is less stressfull on the wires

    EDIT: BTW, Ohms law: U=I*R, no P involved there either...
     
    Last edited: Feb 17, 2010
  20. 2Tired2Tango

    2Tired2Tango Tech Monkey

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    The wires are a full circuit, yes. Are they the best ground your system can have... NO they are not. See my post above where I calculate the ground offsets that are possible with an ungrounded system... Like you said the lands on the board are there to keep everything at the same potential... and that's a crucial factor in system stability.

    Just because you can make a plastic case does not mean you should.
     

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