Cpu power behaving strangely

July 8, 2012 at 04:02:38
Specs: Windows 7
Hi Guys...!!

I am experiencing a strange problem.
1) I plugged the CPU power cable to power board and switch is off.
2) Now i switched on the CPU buttton and strangely, the CPU is started running
3) I verified the power board switch with other electronic appliances the power board and switch is 100% fine.

4) My CPU is working fine but problem is without switching on the main supply power, when i press power button on CPU,it is starting ..... WHAT DO U SUGGEST GUYS....??


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#1
July 8, 2012 at 04:09:31
Wait so its powering on when the power supply is not connected to the mains or what?

I am a hardware guy not a software guy but i try to help.


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#2
July 8, 2012 at 04:13:17
And you mean desktop base unit right, the CPU is a chip with a hundred pins on the bottom underneath a heatsink and fan.

I am a hardware guy not a software guy but i try to help.


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#3
July 8, 2012 at 04:22:07
You have discovered free energy. Cash in on your discovery.

Alternatively, your mains power switch is broken.


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Related Solutions

#4
July 8, 2012 at 06:41:53
THIS is a CPU. Notice it has no cables or buttons. I doubt your problem has anything to do with the CPU. Other than that, your question is so poorly explained that I don't know what to tell you.

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#5
July 8, 2012 at 07:51:16
The power supply has capacitors inside that can and do store energy. Shutting off the On/Off switch on the PSU simply interrupts the AC coming into the PSU.

When you press your power switch the residual energy in the capacitors is discharged. This may cause some momentary movement of fans.

This residual energy is the reason why motherboard makers recommend that you do exactly what you describe before working on the innards of your PC.


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#6
July 8, 2012 at 08:23:55
The term CPU is frequently mis-used
riider has pointed you to what a CPU actually is.

The computer case that most if not all your computer's components are installed in IS NOT A CPU - it's just a computer case.

I'm guessing from your poor descriptions that...
- you have a desktop computer, not a laptop or netbook computer

- the power supply installed in the computer case has a power switch on it, on the back of the computer case.

- when you plug the AC power cable, that is plugged into a source of live AC power on the plug end of the cable, into that power supply's socket for that on the back of the computer case, if the power switch on that power supply on the back of the case is switched off when you do that, the computer does not start up.

- in that situation, when you then switch on that power switch on that power supply on the back of the case, the computer starts up automatically.

How your computer behaves when AC power has been restored to it's power supply, when the switch on the power supply itself is switched on, whether it's when it's AC cord is already connected and has live AC power when you switch on that switch, or when that switch is already on on the power supply and you plug in the AC power cord that is connected to live AC power, depends on a setting in the mboard's bios Setup.
In that case, that setting in the bios is set to start up the computer when AC power has been restored.

However, the computer MAY start up automatically in any case even when that setting in the bios Setup has been set to NOT start up the computer when AC power has been restored, if switching on the power switch on the power supply itself, or plugging in the cord into the power supply from a live AC source when that power switch on the power supply itself it already on, or even when you switch on a power switch on something the AC power cord is connected to on it's plug end, if doing that produces electric or electronic noise, which the mboard interprets as you having pressed the power button for the power switch on the front of the computer case.

Look in your bios Setup to see if a setting is set to start up the computer when AC power is restored.
If it is set that way, if you don't want the computer to do that, change that setting, Save bios settings.

If it is already set to NOT start up the computer when AC power is restored, then your computer starting up automatically is caused by electric or electronic noise being produced by whatever you did.
As long as you don't do whatever caused the electric or electronic noise to be produced by whatever you did, when the power supply is getting live AC power and it's switch on, on it's own switch, the computer will not start up unless you press the power button on the front of the case.


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#7
July 8, 2012 at 09:54:54
Sorry Guys..
Let me describe my problem now correct..!!

I have a DESKTOP PC. Now when i plug in the AC power cord of computer case to power supply and my power supply switch is off.

Now there are two button on the front side of computer case, ON button and reset button..

When the power supply switch is off and now i press the ON button on front side of computer case, the computer starts running, which should not happen becoz the power supply switch is off.

This is only happening when i plug in my computer case power cord.... when i tried with other electronics appliances it is working fine... what i mean to mention here is power supply board and switch is 101% fine...

I feel something is wrong with my computer case power unit...PLEASE SUGGEST ME WHAT TO DO..??


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#8
July 8, 2012 at 10:52:23
A little late but another link for a picture for a CPU as Riider's link didn't work.

http://www.google.co.uk/imgres?um=1...
You switch either is not wired, the contacts inside the switch are stuck or the switch is somehow jumped so that it has no effect.

I would replace the power supply as i could be seen as faulty as the switch is not working.

I am a hardware guy not a software guy but i try to help.


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#9
July 8, 2012 at 12:31:01
nikki

Does the computer STAY running or just make some noise and then stop?

Are you sure you are shutting off the power supply. Try the same thing with the switch in the other position.

If you have a voltage selector switch be sure it is set to the proper voltage for your area.


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#10
July 9, 2012 at 06:55:49
"Are you sure you are shutting off the power supply. Try the same thing with the switch in the other position."

Most on / off switches on the power supply itself are rocker switches. The two sides of the rocker switch rocker are usually marked with a long dash and an O - when the side with the long dash is pressed in so that it's closest to the case, the power switch is ON.

"If you have a voltage selector switch be sure it is set to the proper voltage for your area."

Most power supplies have a recessed slide switch for that, that is not easily moved unless you use a tool to do that. It's usually red. It must be all the way one way or the other such that the AC voltage is appropriate for what the AC voltage is where you're using the computer and you can see that incised on the switch slider - 110 or 220 .


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#11
July 9, 2012 at 09:13:23
Hi everyone....

my power supply and switches are working 101% fine...i tried with all other electrical appliances... its only strangely behaving with the computer case power cord...

my desktop is working very fine without any noise...... the only problem is the my desktop computer case is running even i switch off the power supply switch...!!


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#12
July 9, 2012 at 14:09:35
Check the outlet you are using to verify it is wired right. If the Neutral and 120V are crossed then the switch may not be interrupting the circuit.

If that is the case your computer case may be carrying live voltage.

Go to the hardware and buy a tester for your outlets.


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#13
July 9, 2012 at 14:45:56
To Othehill, you mean Earth/ground, neutral sends back the electric to the power station.

I am a hardware guy not a software guy but i try to help.


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#14
July 9, 2012 at 14:56:55
jay

I meant what I said. if the hot and neutral are crossed the switch probably is not interrupting the current.

The switch may be interrupting the neutral instead. The circuit can still be completed by way of the grounding wire.


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#15
July 9, 2012 at 15:15:43
If hot or live was switch with neutral, wouldn't it ground straight away because the current is going the wrong way?

I am a hardware guy not a software guy but i try to help.


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#16
July 9, 2012 at 15:23:29
It would depend on how the PSU is built.

From the explanation in #11 it seems that either the switch is defective or the wires are reversed in the outlet.

I asked if the same thing happened with the PSU power switch in the opposite position but that question was not answered.


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