Does PSU on == Computer on?

[iwodo]

If the PSU is ON ( Powered UP ) does it mean in any scenerio the Computer should boot up?

 

[Matthias99]

I'm not following your question.

The PSU doesn't turn on until the motherboard tells it to (usually by you hitting the power button, although some BIOSes allow you to set it so that if a power outage occurs, it will automatically power back up when power is restored). So, if you hit the power button and the PSU turns on, SOMETHING is working, but that doesn't mean the system will necessarily boot up if it's having hardware problems.

 

[Feep]

it means the psu is working, at least to some extent. Why would that mean the rest of the computer is working. Please clarify the question.

 

[iwodo]

Becuase my power switch Pin on My motherboard is damage. ( And changing or buy or RMA is not an option for me )

So i found a way to turn on the PSU was by puting a wire in between the Green Wire ( Power ON signal ) in the PSU plug and to a Black wire ( ground ).

Now when i switch on the PSU, My motherboard turn on but the debug card is all red coded. I have had this error before when i installed my GFX card too tight. But now i have fix that and i am still getting this error.

So i am wondering if PSU on is nessary = to PC should boot up.

I remember in the old days when you switch off a computer you had to switch the power off yourself as well............

 

[Feep]

Did the computer ever work after you modded the wiring. Becuase if it didnt I'd say you messed that up and your MB didnt like it.

 

[KillaKilla]

Originally posted by: iwodo
Becuase my power switch Pin on My motherboard is damage. ( And changing or buy or RMA is not an option for me )

So i found a way to turn on the PSU was by puting a wire in between the Green Wire ( Power ON signal ) in the PSU plug and to a Black wire ( ground ).

Now when i switch on the PSU, My motherboard turn on but the debug card is all red coded. I have had this error before when i installed my GFX card too tight. But now i have fix that and i am still getting this error.

So i am wondering if PSU on is nessary = to PC should boot up.

For the 'PSU=on' to return (- wire) boot, it must also have the right power-good connection (I don't think you can get around this by shorting it to a - wire; this (the power good) detects shorts as well as if the MB is accepting the PSU power. If this (power-good) detection is not accepted, it will act like it's a short(it will start for a second, then shut off ASAP). Remember that PSU-on to -wire short? that is the same thing as pressing the power button(where the motherboard sees this, and pulses that PSU-on cable once to turn it on. So keeping it shorted is the same as pressing that power button over and over really, really fast. This is what happens for the PSU:

Power on (the PSU starts to turn on)

**ALARM** (the power good wire is not responded to, it thinks there's a short. It turns off, hoping to spare your parts)

It does an emergency off, cutting power (like unplugging it from the wall)

It detects that the PSU-on wire is shorted(like a normal pressing of the power button) and the cycle starts over again.
The net affect of this is that you'll get your fans going at half speed/voltage, because the PSU is only on for about 1/2 the above cycle. You HDDs will not spin (unless they are incredibly cheap ones) becuase they are not getting good power. Your MB will get 1/2 voltage across the lines, and your diagnostic card is going nuts (remember, still running at 1/2 voltage).
Perhaps your power good pin is not getting the right signal from the motherboard. I think they'res some cuircitry between the power button connector on the MB and the PSU-on wire/ This cuircitry is not being activated (your just skipping the MB part ) and the MB isn't running the Power-good routine.

 

[farscape]

Old AT style MBs needed a "maintained" switch to turn on the PS.

ATX types use a "momentary" type switch to start the PS. Power is always supplied to the MB in an ATX system (unless your PS switch is off or unplugged).

All it is waiting for is for you to push the button - board/circuitry/"relay" senses power good signal and "turns on the contacts" and away it goes. It needs power from the PS to sense power to turn on.

Over-simplified - but hope it helps.