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Problem turning the computer on!

by Kentini / August 24, 2005 3:16 AM PDT

Hi.
About a week ago, my computer would just TURN OFF by it self without warning. Than it would later just Flicker ON and FLICKER OFF right away (total time between ON and OFF: 0.5 sec) At first I thought it was OVER HEATING but later I found out that I needed a new POWER SUPPLY to accommodate the needed power. SO, I purchase a 400 watts Antec Power supply and replace it, it works!

The concern that I have is that after all of this, some time my computer would turn on but it will not recognize any thing (IE Monitor, Mouse). It does usually occur when I move my computer around the house. This was resolve by disconnecting all the power cables from to power supply to the computer components (IE mother board, hard drive).

What is the problem with this? And how can I prevent this?"

My computer Spec:
P4 2.8 ghz
1gb ram (kingston)
1 UATA HD
1 SATA HD

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It may be a form of Power Mgt glitch.
by Ray Harinec / August 24, 2005 4:08 AM PDT

Rather than disconnecting the outputs from the power supply. After a move, when you plug the AC power to the power supply again, turn the computer ON. If you get the glitch, unplug the power supply [from the AC line] for about a minute, then plug it in again and turn it on.

You didn't really explain, in sufficient detail, the indications when the bad startup happens. Do fans run and keep running hard drives run, power on LED light etc, etc??

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more detailed
by Kentini / August 24, 2005 4:41 AM PDT

sorry, ok
this actually happen yesterday afternoon after I bought a new desk and have to move my computer out of the room.

1. I unplug everything (external) and move everything out. On the way of moving my tower out, I hit it to the door frame( more of a tap, if that matters)

2. new desk set up and moved everything back and plug in everything.

3. Once I press the "On" button, the tower starts, fans running, BUT my monitor did not response(I always leave the monitor on)and so did the mouse and keyboard.

4. I turn it off and called my friend, he advise me to replug all the cables from the power supply to everything, HD Motherboard etc.

5 I turn it on again and I get the "glich" the LCD light on monther board stays on but all the fan and everything else just flick on than off right away.

Note* this also happen when I use my old power supply but fixed with a new one.

6. I repeat step 4.

7. Turn back on and its working fine again. . . .but now am worry so I seek help and explanation here.

Thanks I hope this is enough info, if not, am more than glad to explain more.

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I may have accidently posted my sick humor
by Ray Harinec / August 24, 2005 5:24 AM PDT
In reply to: more detailed

accidently before discussing the problem, sorry. [re #4 always calling your friend?]

OK, the LED on the mobo simply tells you that the 5 volt standby power is present on the mobo. That voltage is ALWAYS there as long as the power supply is plugged into the AC power. That voltage is what powers the logic cicuits that allows the Power Supply to turn on by a simple momentary push of the power switch. It also provides the logic power for the Power Mgt functions so that such things as Wake on LAN, sleep mode and recovery, hibernate and recovery etc can function.

Go into your BIOS and see what Power Mgt settings you are using. Try setting to "User Define" and not enabling any of the options.

There is a possible power supply problem that could cause this. The power supply, Pin 8 [PWR OK, or Pwr GO] holds the master reset line down [does not allow booting to proceed] for 100 to 500 milliseconds to allow all of the voltages to rise from zero volts to the correct value. This time is required to allow the output capacitors to charge so that the CPU isn't trying to unreliably execute things in a low voltage state. Thus, it is possible that the first try partially charges the capacitors and then during the second try the capacitors get charged to a high enough voltage to release the PWR OK.

Might try waiting different periods of time between the first and the second try. Just last week someone posted where he had that problem when the system was off overnite, elsewise, off for only a few hours worked fine. [my speculation is that although the charging path of the capacitors is an intentional path and the time constants are known, the discharge path is not defined and is only by leakage paths through solid state devices, thus the residual charge [starting point of the recharge can vary as a function of OFF time]

Funny but I had a ANTEC where all of the voltages came up to spec and stayed on, but the system wouldn't boot because the supply never released the PwrOK line. [they replaced it under warranty].

If you feel certain that the supply is the problem and is not still under warranty, I would just live with the problem.

If you have a DVM and understand the voltages that would be measured inside of logic circuitry, you could use it to see if Pin 8 voltage is different after a bad turn on than after a good turn on. It won't be a simple zero volt, 5 volt type reading, will vary by the type of circuit the supply uses.

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