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Resolved System will not boot

Discussion in 'PC Hardware' started by Gordon, 2010/01/25.

  1. 2010/01/25
    Gordon

    Gordon Well-Known Member Thread Starter

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    System will not boot

    My PC is normally connected to a APC battery back up. The PC failed to boot up yesterday. The cooling fans would start, run for a few seconds, then turn off. I finally got the PC to boot up after disconnecting the main power cord from the tower, then plugging it back in. When it did came on, boot up and load Windows, all voltages were at the normal readings. So I assumed that maybe the power plug was loose and I had fixed the problem.

    This morning the APC backup started sounding the alarm with the 'overload' light flashing. The PC was powered off at the time and had not been powered on yet today. Nothing connect to the battery backup was turned on. I removed the APC battery backup and plugged everything into a surge protector. When I pressed the power button on the PC, I got the fans to come on, run for a few seconds, then turn off, just like yesterday.

    When I plug in the APC battery backup with nothing connected to it, it is now flashing the 'replace battery' light. I ASSUME that the APC unit failure has nothing to do with the PC power up failure. However, I felt that maybe it does mean something to the experts.

    Next I replaced the CMOS battery and reset the BIOS, removed and reconnected the 24 pin power connector to the mother board, took the surge protector out of the loop and connected the tower directly to the wall outlet, and used a different wall outlet. Non of the above had any effect on the PC boot failure. I did finally get the PC to boot up and load windows and I think it was just a matter of enough attempts.

    The motherboard is a MSI K8N Neo4-f. The power supply is an Antec smartpower 450 watt. All PC parts were purchased in May 2006 so everything is going on 5 years old. I have looked over the motherboard and do not see any swollen or leaking capacitors.

    Now I am afraid to power down until I have some spare parts on hand.
    But what parts? Does this sound like a power supply problem, a mother board problem, or something else? I live in a remote area with very limited local PC parts so I will most likely have to order replacement parts online.

    Any suggestions or advice would be appreciated.
    Gordon
     
  2. 2010/01/25
    Dennis L Lifetime Subscription

    Dennis L Inactive Alumni

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    Hi Gordon
    You have done a good job eliminating APC, surge protector, 24 pin connection, and wall power source. The rest will have to be trial/error/replaced.
    Start with power supply. 5 years old PSU is /has hit end of life. It runs your system after consecutive attempts because components have warmed up, lower power draw on start-up.
    Possible RAM. But if stable after multiple attempts would imply RAM working after warm up. ... my concern, "no read/report" when cold. My guess is still PSU
    Mobo - if stable after warm, not concerned ... yet.

    Backup power unit - may want to hold off until above is corrected.
    Simple test ... hook ACP to a good stable box / 110v wall power. With computer on, pull out 110v wall power to ACP ... does computer continue to run? For a period that works for you?
     

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  4. 2010/01/26
    Gordon

    Gordon Well-Known Member Thread Starter

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    Thanks for the reply Dennis.

    The battery backup is not a concern at this time. I can play with it, repair it, or replace it at some future date. I need my PC to be working in a dependable state.

    I did notice a new symptom today. Sometimes the power on light on the PC blinks on and off at a rate of about once per second when the PC is shutdown. If it is blinking, it is not going to power up and boot into Windows. That's when the cooling fans turn on for a few seconds and then stop. If I can get the power on light to turn off and stay off , then it will power up as it should. I have found that by removing the 115v input to the PC for a few minutes will stop the power light blinking and allow a normal power up, most of the time. I had to fashion a probe extender for my meter so I could probe some voltage readings. Now that I have the probe extender ready and I have all the voltages recorded, both with the PC running and with it powered off, the problem has not occurred again. I am beginning to wonder if this is more of a failure during the power down / shut down cycle that sets the conditions that prevent a normal power up.

    I am ready for it to fail again, which I think it will, so I can get some voltage readings. Maybe that will help me decide what parts to order.

    Thank you for your help. I will post a reply to this thread when I get more information on my problem.

    Gordon
     
  5. 2010/01/26
    qwester

    qwester Inactive

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    What is your ambient (room) temperature? Is your CPU fan working? You can feel the air exiting the chassis if it is working. Use wet fingers for greater sensitivity. Has the dust and lint been removed from the CPU heat sink? Power supply fans start and then stop running due to an under voltage or over temperature condition. I would suggest a newer power supply. Many computer recyclers sell used power supplies at bargain prices. Try ebay for power supply and/or CPU fan.
     
  6. 2010/01/29
    Gordon

    Gordon Well-Known Member Thread Starter

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    I replaced the power supply. Problem fixed.

    It looks like the problem was caused by a low voltage on the +5 volt line. My normal reading for the +5 volt line was 4.96 v. However, with the PC powered off, the reading on the PS-ON line, pin 16 of the 24 pin connector, would drop over time. When that line dropped below +4.86 volts, the PC would not power up. The new power supply reads +5.05 on that pin and it holds steady at 5.05 volts.

    Qwester,
    Thanks for the suggestion. I really believe that the life span of solid state chips is directly related to heat, so I keep the temps inside the PC as low as I can, within reason. Right now the room temp is about 70f, the CPU is at 82f and the chip set is 84f.

    Gordon
     
  7. 2010/01/29
    qwester

    qwester Inactive

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    Power supplies and temperature and dirt

    Thanks for the feedback, Gordon. I am not sure that chips degrade seriously at normal ambient temperatures. Maybe Alabama's climate is involved. Here in Illinois it's probably less of a problem. What I find to be far more serious is pet hair, especially from cats, and lint from the clothes dryer. It will block up muffin fans in power supplies and cpu heat sinks in less than a year. If your power supply has ball bearings in the fan they will become noisy sooner if it is choked with lint or fur due to high heat effects on the lubrication of those bearings If the fan has sleeve bearings the oil will cook out of the sintered bearing and the fan will quietly slow down causing temps to rise. Make sure your clothes dryer is vented to the outside and brush your cats frequently.(notes from an old mechanical engineer)
     

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