Accidentally left PSU Switch "ON" when unplugging PC...

Oinkusboinkus

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Jul 8, 2012
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Hello,

Hello all. Just a quick question. I am usually religious with making sure that my PC is powered down and the PSU switch is turned off before unplugging it and doing any work inside the case.

This week I had upgraded memory and put in a new case fan, and also cleaned the other fans. When I had gotten done putting in the fan, I noticed that I had left my PSU Switch in the "ON" position. Of course, I DID power down the PC before unplugging it, but left the PSU switch itself in the on position.

I plugged everything back in and rebooted, everything is running perfectly.

Just wondering if I did anything bad to the PSU by doing that this one time. All components are running fine, and all fans are humming normally, everything looks A-OK.

Thanks!
 

Oinkusboinkus

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Jul 8, 2012
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WOW, I posted my question like FIFTEEN seconds ago! 4Ryan6, thank you so much for that blazingly fast response, you are a true gentleman!

Thanks for the reassurance, I was sort of sure I was ok, but wanted to hear it from someone else who knew. This was literally like 1 time out of 100 it happened where I forgot to follow that step before unplugging.

Thanks again Ryan.

Oinkus

 

InvalidError

Titan
Moderator
All the switch does is breaking metallic continuity between the power cable and internal circuitry, which is exactly what pulling the plug does anyhow.

The only difference between the two is that the switch is designed to minimize make/break arcing while the plug isn't. This is mainly a concern while plugging in where there may be a huge inrush current surge while input caps get charged up and if contact is made slowly, the arc may melt/vaporize some connector metal which can cause significant premature wear and create some 'cracking' noises that may spook people. The same thing happens inside switches but because switches have very fast 'snap' action, the amount of time the arc may exist is much shorter and the amount of damage it may cause is much less. Switch contact points may also be made of tungsten to further minimize sputtering.

When disconnecting a PSU that is already in soft-off state, there isn't much current going through the cable (only what the 5VSB needs) and there would be little to no arcing.

Long story short: the switch is almost optional, it is mainly there to spare cable connectors some arcing while plugging it in.
 

Oinkusboinkus

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Jul 8, 2012
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Ah, ok thanks for that explanation of how it works. That was my main concern, because I also plugged it back in with the PSU switch in the "ON" position as well, not thinking. Only after I was up and rebooted, and everything was fine, I said "Ohhh, why did you do that?" lol....
 

Oinkusboinkus

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Would plugging it back in that way one time hurt it? I'm just being paranoid. The PSU is like a year and half old, but it's a really good one, a Corsair 1200w. I want to keep if for at least another couple years, barring I don't do anything else stupid like this stunt. Like I said, it was a 1 in 100 thing where I wasn't thinking.
 

InvalidError

Titan
Moderator

The main danger is in the AC cable connectors. Repeated "hot" plugging with repeated arcing will damage the contact surfaces both in the plug and receptacle, the arc-roughened and hardened surfaces will have more friction and scrape each other, the scraped surfaces will be more prone to arcing and things can eventually degrade to the point where surfaces can no longer hold a proper electrical connection which can lead to becoming a fire hazard.

For things to get to that point though, you would need to hot-plug/unplug hundreds of times, it is not something that will happen overnight from forgetting to use the switch a few times.
 

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