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Fried CPU and/or motherboard.. hard to diagnose

Discussion in 'Hardware' started by jiolasa, Aug 31, 2001.

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  1. jiolasa

    jiolasa Thread Starter

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    Alright, this may be long.

    I'm running a system that I built about 8 months ago, and it has been working fairly well.

    Soyo Socket A SY-K7VTA Motherboard
    AMD Athlon Thunderbird 900mhz processor
    Antec Case/250w Power supply

    I don't believe the other parts of the computer are important, because they seem to working well. Recently I began to have trouble with my computer locking up, and I noticed it was running at a slightly higher temperature than usual.

    At this point I had a generic CPU fan (Coolermaster, don't know the exact power) and no case cooling fans. So I bought a new (Antec Jet Cool ) CPU fan and a new Cooling fan for the case.

    In the process of removing the old fan, the screwdriver being used to remove the old fan slipped and just barely dinged the motherboard. Probably not enough to break anything, no visible marks.

    When we finally got everything installed and plugged in, we powered on the computer. It started up all the fans, etc., and after about five seconds it powered on the hard drives. It then immediately shut down. I don't know whether or not it had completed POST because the speaker on my case doesn't work so I hear no beeps no matter what. THe monitor never comes out of suspend mode during this time.

    The first thing I did was to unplug all the fans and see if I had fried the power supply. Still the same problem.

    I tried everything.. I tested other power supplies, and they did the same thing. So it's not the power supply. I've removed all cards plugged in to the motherboard, and unplugged all accessories (hard drives, cd-rom, etc.) Still the same problem.

    So I tried taking out the CPU. Once I took out the CPU, the computer stayed on after being started up.

    So this is all I can think of:

    A) Fried CPU - either the cpu is smart enough to shut down the computer when its plugged in, or the motherboard is smart enough to shut down the computer when it detects that the CPU is fried.

    B) Fried Motherboard - that would mean that the CPU is smart enough to recognize that the motherboard is fried, and would shut down the computer.

    Anyone have any ideas?

    thanks a ton

    -matt

    Oh yah, also I tried removing each stick of RAM individually, with no results. So I removed all of them.
     
  2. brianF

    brianF

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    did you redo the heatsink/fan combo, if installed improperly the cpu would immediately overheat and the bios would shut the machine down.

    Got another processor to try.
     
  3. jiolasa

    jiolasa Thread Starter

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    Yes, it was the entire combo. I have considered that as a problem, but I checked and rechecked the heatsink/fan to make sure it was in contact with the CPU, was seated correctly, etc. etc. and also used the.. I'm forgetting the technical term, goop for assisting in the heat transfer. Right now that seems the best bet, because the heatsink/fan combo already had melted "goop" on it, which makes me believe that CompUSA sold it to me used.

    I unfortunately have no other processors to try it with.. and really don't want to have to shell out another 80 bucks for a new CPU, if it turns out its not the CPU that's busted.

    thanks
    -matt
     
  4. brianF

    brianF

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    Hope you didn't use too much thermal paste, that can cause more harm then good. You only want a thin coat
     
  5. cavp

    cavp

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    Sure the screwdriver didn't do anything to the mainboard? Check the circuits around the place where it hit the mobo, perhaps it made two pins of a circuit shorted, and that could be the problem... and this mean, usually, that you would need another mainboard (I hope not)... Good luck
     
  6. jiolasa

    jiolasa Thread Starter

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    Thanks a lot for your help..

    That very well could be it. If you use too much thermal paste, does it lose its efficiency as a conductor? (makes sense..) I don't think there was too much, but that's also a possibility.

    So .. I guess it comes down to, I have to find some way to figure out which it is. Anyone know of a way to test a motherboard and/or CPU without buying another motherboard or CPU?

    Well I just checked the mother board out again.. Now I do see a very small mark on the board, it goes across three circuits. None are cut, it doesn't LOOK like any of the shorted together.. but there's probably no visible way of checking that, is there?

    If that were the problem (shorted circuits on the mainboard), would there be any possibility that my CPU is ok? Becuase if there's no damage a shorted circuit could do to a CPU, I could borrow my friend's athlon and see if it works on my motherboard...

    Thanks again for all your help.

    -matt
     
  7. Shadow2531

    Shadow2531

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    don't know for sure, but some motherboards use the cpu fan's rpm reading coming for the 3rd wire on the fan connector so if the fan dies, the motherboard will power off everything right away. So if the fan you bought draws a lot of amperage and you had to hook it up directly to the power supply with say a 3pin-4pin converter, the motherboard wouldn't be getting any rpm reading for the fan.

    Maybe someone can go into more detail on this one if legit.
     
  8. jiolasa

    jiolasa Thread Starter

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    AHH!! Thank you so much shadow! Tried sticking the old fan on it and it all worked beautifully (maybe running a little warm, but it worked.) Thanks for all of your help, it was really useful.

    So I'll go make CompUSA gimme my 30 bucks back.

    -matt
     
  9. Shadow2531

    Shadow2531

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    Well you can still use a kick butt fan hooked up directly to the power supply, but you will need have the one wire going to the motherboard fan connector that reads the rpm. Not sure if there is a custom cable you can buy like that, but you can always make one yourself.

    You said you tried your old fan, but how was the new fan connected? To the power supply like I was suggesting? Or the fan was connected to the cpu fan head, but only had 2 wires which would have no rpm monitor or What?

    Just curious.
     
  10. jiolasa

    jiolasa Thread Starter

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    I'm pretty sure there isn't a cable to buy that does that.. but you're right. How do you hook up the two power cables to the power supply ... ? I think that may be beyond me, if it includes taking apart the power supply and splicing in wires. The new fan used the same three-wire connector, connected to the mainboard through it's fan slot. Somehow I guess the rpm monitor didn't work.. or the fan wasn't spinning fast enough to satisfy the motherboard's standards.

    By the way, anyone know of a way to monitor the amount of voltage being drawn from your power supply (without monitoring each individual cable , that is...)? I'm running a 250w power supply, and after buyinging a couple new cooling fans, Ive realized that I'm not sure whether or not my power supply can handle them.

    thanks

    -matt
     
  11. stnwerks

    stnwerks

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    You could try using you old fan as case exhaust fan, that way its hooked up mb will work. Only it defeats shut down protection!
    A thought Steve
     
  12. Shadow2531

    Shadow2531

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    it wouldn't hurt to get a better power supply for your power hungry tbird.

    OK maybe there was just something funky with that fan you bought then.

    but you can get a 3 pin to 4 pin converter to hook the 3pin fan up to your power supply which is usually done on high rpm fans because they draw a lot of amperage and could possibly fry part of your mainboard. It's a better safe than sorry situation.

    If do hook up the fan to the power supply and the motherboard does require rpm reading of fan to run properly then you would have to make a custom connector. All you would need is a 3 to 4 pin converter and a 3 pin connector. But you shouldn't have to do all that. I would just get a good fan that works correctly with the mainboard fan header.

    So good luck and make sure you keep that tbird cool.
     
  13. cassul

    cassul

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    I noticed the same problem when i was messing around with overclocking on my system. When i went too hight with the clock speed my system would just lock up.
     
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