Leave power supply plugged or unplugged when working in your computer?

[Ad Hominem]

Title. I know that most manuals that come with hardware will tell you to turn the PSU off and unplug it when working inside of your computer. I assume this is so you don't accidentally get shocked (even though you probably couldn't feel a live 12 volt rail even if you were dripping wet), or so you don't accidentally create a short to other components through your body and fry them. I'm more curious about what would happen with static.

If you did happen to have a static charge on your body and you touch the case before you put hands on a component, you would discharge that static to the case. But with the power supply unplugged, there is nowhere for that static charge to go. Hopefully your components would be insulated well enough from the chassis at ground potential, but that still seems like a bad thing to me to let loose a large change in potential like that.

I'm thinking if you were to leave the PSU switched off but still plugged into the wall, that would allow a ground path for that static charge to go away, since the switch (I'm assuming) most likely only breaks the hot line coming into your power supply from the wall, and the neutral path and ground path would still be intact.

[Jaunitta 🌸]

The real answer is…it depends
Standing on carpet could be dangerous so unplug the AC.
You can accumulate an average of 10,000 to 12,000 volts just walking across carpeting.

Static electricity refers to the buildup of electric charge on the surface of objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge. And it’s that discharge that can ‘zap’ or ‘fry’ your computer components, rendering them inoperable.

To give you an idea of how little static electricity needs to be generated to cause harm to your computer components, it takes as little as 5 to 10 volts to cause damage inside your computer. In order for you to even feel the presence of static electricity, the level needs to be above 1,500 volts.
I wear anti-static wrist band and unplug ac.
Wikipedia a good source of facts?
https://en.wikipedia.org/wiki/Static_electricity

[_I_]

unplug

as long as you and the case share a common ground you will not damage anything
just touch the case occationally, and before touching anything inside it

when installing components handle them by their ground edges

[Talby]

I leave the PSU switch off, but leave it plugged in - chassis/earth ground keeps things safe when you grab the chassis if you don't have a strap. Been doing that for decades, never a problem when you do it right.

[_I_]

doesnt make a diff if the case is earth grounded, it just needs a common ground with the one working on it

[Talby]

^ as an electrical engineer, if your outlets are not earth grounded - that's an entirely separate issue you probably should address asap.

Originally posted by Ad Hominem:

...I'm thinking if you were to leave the PSU switched off but still plugged into the wall, that would allow a ground path for that static charge to go away, since the switch (I'm assuming) most likely only breaks the hot line coming into your power supply from the wall, and the neutral path and ground path would still be intact.

Yes, this is the earth ground that is common in most houses built after 1970, only older homes without the 3-prong outlets need the adapter which will depend on being grounded to earth at some point - usually in the basement with a wire that is chained to a spike or rebar that connects the metal wiring sheath the outlets are connected to literally into the ground.

[Ad Hominem]

I will generally always wear the anti-ESD bracelet that has a wire with a gator clip at the end that I connect to my case when I work on my PC. I was just thinking it would probably be safer if the case was also at ground potential rather than just kinda a floating ground, idk what else to call it. That way any charge that gets built up doesn't just linger on the case. But the only way you could do that is if your house had proper earth grounds on the outlets and you left the PSU plugged in, which kinda goes against conventional wisdom. Maybe I'm overthinking it though, and both are probably just fine.

[tacoshy]

I even jeep my PSU on and plugged in when working on my PC. Sometimes I even change stuff while it is running. You just need to know what you do, how you do it when to do it.

[CreamyJuices69]

Hey all, I am an electrican's apprentice with 1.5yrs of experience in the usa and I went to trade school for a year, got into building gaming pcs and have worked on mine for the last 8 months. Having the power supply plugged in while working on pc components even when switched off is something i would not do as in my eyes there are easier methods and safer ways of going about eliminating static electricity. I personally clip my anti-static mat to my pc while its on it, then ill clip the anti static wrist strap to the the edge of my case and work like that. The reason why this works is due to electrical bonding, which means that me, and the components inside the pc are set at equal potential meaning the voltage between me and the computer is the same. This method works best if you can work without socks on, standing on anything thats not a carpet and working on a wood or similar hard, non conductive surface. The other method i would suggest if you had to work on a carpet or a metal table is to ground yourself, please please please for the love of everything do not pull off the alligator clip on your wrist strap and try and plug yourself into a live or even switched off or even dead circuit, there is no need and all it will do is increase the risk of you getting badly shocked for no reason, clip yourself you a main water pipe in your house, or a non painted part of your radiator maybe, that should allow you to be grounded as they literally travel out of your house and directly into your ground, and is actually used as one of the grounding electrodes for the whole service of the building so (Section 250.50 of the national electrical code), there you go. Hope this helps.

[DeadPhoenix]

Front part of my PC is on carpet. But backside is on a stone floor. I always turn off my power strip when not using my PC, but leave the cable plugged in. Haven't had issue's with it for the past 15 years.

[CreamyJuices69]

@Deadphoenix, im not talking about day to day use i am talking about when you replace parts and work on things inside the pc.

[DeadPhoenix]

Originally posted by Turbo Beef:

@Deadphoenix, im not talking about day to day use i am talking about when you replace parts and work on things inside the pc.

When switching out parts, always unplug the power cable, and put on a wooden table.

[Ad Hominem]

The only good reason I can think of to keep the power supply plugged in but switched off, either at the PSU or switch off at the power strip, is that the ground is carried all the way out. Otherwise just unplug the machine, hook the ESD bracelet up and touch something else that's grounded.

But lets be honest, PC parts arent as fragile as they were 30 years ago. When I started building PCs 15 years ago I would build them on carpet with socks on in the winter with no ESD and never grounded myself. Never shocked any parts to death. Most traces on PCBs are covered or laminated or whatever, just don't finger ♥♥♥♥ the pins on your CPU or graphics card.

[_I_]

esd bracelet is pointless if nothing you are working on is using earth ground

only components designed back in the 1970-mid 1990s were static sensitivie

[Rumpelcrutchskin]

I have always just unplugged, I`m not a freaking Linus to swap components while PC is running, he is not a good role-model when it comes to handling the components, mostly because he doesnt have to pay for those components and you have to.

[Ad Hominem]

Originally posted by Rumpelcrutchskin:

he doesnt have to pay for those components and you have to.

Bingo. I'd go rogue and do all sorts of dumb stuff too if people just sent me hardware to play with. Same as Jayztwocents who took a heat gun to a graphics card just to see what the throttle behavior was.