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power supply off, cpu can still turn on?

By zekeHLM ·
When the switch in the back of my power supply is turned off, i click the power button and the cpu and fan attempt to turn off, then turn back off. why is that? how do i fix it?

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power supply off, cpu can still turn on?

by TheChas In reply to power supply off, cpu can ...

There are a few possible answers here.

You say the system attempts to start-up, then shuts down.
If so, the most likely cause is residual power stored in the capacitors on the motherboard, and in the power supply.

Capacitors act as small batteries.
They store electrical energy.
The larger the cap, the longer it takes for the energy to drain away.

What happens if you wait 1/2 hour or longer after turning off the power switch?

If nothing, then there is nothing wrong with your system.

If you want / need the system to drain down faster, you will need to increase the load on the standby power circuit from the power supply to the motherboard.

CAUTION: increasing the load on standby power can cause the PC to boot up unexpectedly.

CAUTION: to install a load, you will need to slice into the motherboard power cable from the power supply. This will void any warranty on the power supply.

If the system still attempts to startup after 1 hour of setting with power off, I would suspect leakage across the power switch in the power supply.
The easiest solution, is to replace the power supply.

Chas

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power supply off, cpu can still turn on?

by zekeHLM In reply to power supply off, cpu can ...

wow, now there are some dangerous answers, but helpful :) thanks

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power supply off, cpu can still turn on?

by cglrcng In reply to power supply off, cpu can ...

Yikes there Chas, I usually agree fully w/ your posts Bro., but telling a poster who does not yet know about power storage in a capacitor to splice across to drain away residual juice is dangerous to say the least. Lol. My question is after turning off the power supply switch, why in the world are you then attempting to turn on the computer? If you want to be sure it's off, just unplug that power cord to the power supply.

And no matter what people (old school) will tell you, don't leave it plugged in to work inside the box to give a drain point for SED (static electrical discharge, just unplug it and ground yourself to the case allowing equalization of static electricity), that (leaving it plugged in), also gives a direct in-path for that high voltage 110V too. Should there actually be bleed across that switch or a short in the power supply somewhere, you could get quite a jolt. Ever done that wearing an anti-SED wristband?

Smack yourself in the face and still never get away from the juice. Not at all funny either, saw it happen to someone once.

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power supply off, cpu can still turn on?

by zekeHLM In reply to power supply off, cpu can ...

wow, now there are some dangerous answers, but helpful :) thanks

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power supply off, cpu can still turn on?

by zekeHLM In reply to power supply off, cpu can ...

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