Turning on PSU without flipping its power switch

PSUs: The source of DC power for all components in the PC & often a big noise source.

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TomMe
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Turning on PSU without flipping its power switch

Post by TomMe » Thu Apr 19, 2007 9:49 pm

Hi guys. I was wondering if it is safe for a PSU to turn it on without using its power switch, for example by just plugging it in or using a switch on a power strip? Or can this cause premature failure or something?

I have a couple of old PSUs without power switch in P1 and P2 systems, so for them there's only one way to turn them on. But what about the newer ones like my S12? And what about electric devices in general even? I've always turned on my PC speakers with the power strip. Still working perfectly, but I wonder if this is healthy..
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andyb
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Post by andyb » Fri Apr 20, 2007 1:31 am

Better described in my next post.


Andy
Last edited by andyb on Sat Apr 21, 2007 3:09 am, edited 1 time in total.
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Gojira-X
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Post by Gojira-X » Fri Apr 20, 2007 2:45 am

yes it fine to turn on a PSU, using the powerstrip, although using the power switch is more convenient. I have not known of premature failure that way.

With the old p1 and p2 systems, you will have noticed that old AT boards had a switch that was connected via a black cable to the PSU. That was the predecessor to the modern power on switch at the back and the "soft-power-on" switch at the front.

On old AT boards, when you turned he computer off that way, you was actually turning the PSU off.
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TomMe
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Post by TomMe » Sat Apr 21, 2007 12:54 am

Right, I remember having to push the Power button on those older PCs to shut them down indeed. But I've read a lot about ATX PSU's not having a power switch. I think I have one of them in an older P3 system. What about those?
andyb wrote:this will of course not do any harm if your PC is not already turned on but waiting for power to function.
I'm not exactly sure what you mean by this Andy?

Instead of a fried PC, could my sytem become unstable but still work okay? Perhaps damage the PSU or CPU or..?

Either way, I won't ever do it again.
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andyb
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Post by andyb » Sat Apr 21, 2007 3:08 am

Sorry - bit of confusion, and my description was inaccurate.

AT PC's can be switched on or off using the PC's power switch or any power switch down the line - but you run a hgigher risk of failure due to spikes the further down the line the switch is. The amount of damage your PC would suffer (if any) would be down to luck and your power lines etc etc.

As far as ATX PC's I dont believe it can be done. I tried using a jumper instead of the power switch and turned the PSU on - it started and then shut itself down again, this is because the ATX power switch is very different to the AT power switch.


Andy
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MalcolmC
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Post by MalcolmC » Sat Apr 21, 2007 5:53 am

Funnily enough my latest PC (with an ATX PSU of course) switches on as soon as I turn the power strip on - I don't really want it to, but then again, I am not too bothered, since if I turn the power strip on, the next thing that I always do is turn the PC on - so it saves me around 10 seconds every morning.

I haven't tried to investigate why as yet - will have to delve in to the BIOS settings, to see if anything is set up in a non-standard manner.

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Post by Elixer » Sat Apr 21, 2007 11:08 am

MalcolmC wrote:Funnily enough my latest PC (with an ATX PSU of course) switches on as soon as I turn the power strip on - I don't really want it to, but then again, I am not too bothered, since if I turn the power strip on, the next thing that I always do is turn the PC on - so it saves me around 10 seconds every morning.

I haven't tried to investigate why as yet - will have to delve in to the BIOS settings, to see if anything is set up in a non-standard manner.
This may be due to a Motherboard setting. Generally there's a setting in the BIOS that enables or disables this. The idea is if you were running a server and it experienced power failure it could restart itself afterward (or at least that's what I think it is).

Generally I would say that this it is safe to cut the power from a surge protector. Most power supplies in electronic devices turn off simply by curring the main current. For these devices it's safe to turn them off with a surge protector. Other devices however, like my computer speakers, function slightly differently. As long as they're plugged in, the power supply for the amplifier is always on. What the on/off button does is turn the amplifier itself on and off, the power supply is always active. If the on button on the speaker is on and I plug them in, a distinct pop can noted from the speakers, and this is the speakers getting DC current to them, which can be bad if they get a large amount of it. This means that if something weird was going on with the power from the wall and you plugged them in, something bad *could* happen.

The chances of this however are very low and old AT power supplies' switches function just by cutting the main current so you don't have to worry about them. New power supplies should be tough enough to handle an instant power cut, but I wouldn't do that as it's bad for your hard drives.

TomMe
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Post by TomMe » Wed Apr 25, 2007 4:14 am

I still don't fully understand what you're saying andyb. Sorry, must be me I guess. :lol:
If the on button on the speaker is on and I plug them in, a distinct pop can noted from the speakers, and this is the speakers getting DC current to them, which can be bad if they get a large amount of it.
I have this when my speakers are on and I push the power button of my PC to start it up. Must be normal..

edit: I just noticed a different sort of pop when I switched the speakers/subwoofer on and off with the power strip than the one I mentioned. It sounded like a bubble bursting, while the other is more of a bass tone.

I'm just wondering, some ATX PSUs don't have a power switch and some do. So does it really matter how you turn them on?
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