Is 5VSB on when PC is on?

[Belial88]

Is 5VSB on when pc is on, ie always on as long as psu is plugged in and switched on, no matter pc status? That's it, that's the question, yes or no (i ask because i wonder if the 5vsb turns off and 5v takes over).

I'm trying to power a mod to automate open/closing the side panel using ~5v, that needs to always be powered. I'd like to use the PSU as much as I can, but when I unplug the PC (or uninstall the psu even), I still need to open my side panel to get in.

So if I could run off the psu as long as psu was plugged in, and then battery only when psu was unplugged/removed, that'd be awesome, but if I have to just run off psu only when pc on/battery otherwise, well, i'd need a bigger battery.

Simple question, complicated reason for asking.

 

[Red Squirrel]

Best way is to test, but I think it may possibly still be on at the motherboard level, but the other connectors probably not. I've put fans on the 5v rail before and they turn off with the PC. But if you ever noticed some PCs the ethernet port lights will still be on, and even USB in some cases. So there's definitely still some juice in there somewhere.

 

[Belial88]

Yes... i Know the best way is to test... don't you think I would have done that already if I could?

My DMM was stolen, and I am unable to use my computer due to some modding and housework at the moment. I could wait, but this affects purchasing decisions I need to make now.

Hey what do you know, I said this already in the OP omg just read the op...

ut if you ever noticed some PCs the ethernet port lights will still be on, and even USB in some cases. So there's definitely still some juice in there somewhere.

Yes.... the 5vsb... which is what I'm talking about... My question is if the 5vsb is turned off when the pc is turned on, ie the 5v takes over, or does the 5vsb stay on. I've read conflicting things online about this, on what little info I've found on this. Plenty of posts on what the 5vsb is, but not much on if it stays on when pc is turned on.

Simple question, yes or no. please nothing stupid again. I'm not going to write another essay to justify why I need to know the answer to this. Just answer the question, if you can't do that, you can PM me whatever you want to talk about and I'll be happy to oblige.

edit: seriously it sounds like you have no clue what the 5vsb is, why did you even post in here? of course your 5v turns off with your pc... 5vsb is a different rail from 5v. 5v is part of the psu, 5vsb is literally a psu within your psu, a totally different system. It's meant to power things when your pc is off, stuff like keyboard/mouse/network remote on/wake, usb charge when pc is off, even your cmos. I'm just not sure if the 5vsb is turned off and the 5v put in charge once pc is turned on, which wouldn't matter to most people because the 5vsb line is only attached to your mobo connector so it's only stuff attached to the mobo, but I am planning to splice the purple wire and specifically use the 5vsb if it's always on as long as psu is plugged in.

 

[lehtv]

Simple question, yes or no. please nothing stupid again.

[...]

seriously it sounds like you have no clue what the 5vsb is, why did you even post in here?

You're not going to get many answers if you keep being so judgmental and unfriendly. He was trying to help you out.

I don't know the answer to your question but hope someone else does

 

[Zap]

Dude, chill!

Is 5VSB on when pc is on, ie always on as long as psu is plugged in and switched on, no matter pc status?

Yes, 5VSB (volt standby) is ALWAYS on if the PSU is plugged in and the switch on back is turned on.

That's why some motherboards have LEDs that stay lit, and some systems still power USB ports. Most PSUs have 2.5A available on 5VSB.

If you want to tap into it, it is the purple wire in the 20/24-pin motherboard harness. You should be able to use any ground wire (black).

 

[Torn Mind]

Saying the 5v standby rail is a PSU within a PSU is an entirely inaccurate and nonsensical description. A more proper description is an "always open gateway" of 5v DC current. If you actually saw a basic block diagram, you wouldn't be saying such nonsense.

The 5V rail is always on. I confirmed by checking with a multimeter when the PSU was "soft off" and "on" with the paper clip test using rivets instead of paper clips.

 

[2is]

Your DMM being stolen sounds like Karma.

 

[Belial88]

You're not going to get many answers if you keep being so judgmental and unfriendly. He was trying to help you out.

I don't know the answer to your question but hope someone else does

I don't need many answers, I merely need a single correct answer.

Yes, 5VSB (volt standby) is ALWAYS on if the PSU is plugged in and the switch on back is turned on.

That's why some motherboards have LEDs that stay lit, and some systems still power USB ports. Most PSUs have 2.5A available on 5VSB.

If you want to tap into it, it is the purple wire in the 20/24-pin motherboard harness. You should be able to use any ground wire (black).

Thanks, very straightforward.

Your DMM being stolen sounds like Karma.

Well, internet douchebag, people deserve to lose their $100 DMMs because... they are somewhat rude on the internet to people who don't even read the OP and can't answer the question? Anyone who believes in karma, horoscopes, etc... yea I think you can fill in how smart you are.

I don't mind people being jerks, or ragging on people for being wrong or unhelpful, but passive aggressive comments like that just to inflame, for no reason at all? Sounds pretty useless and just inflammatory.

Saying the 5v standby rail is a PSU within a PSU is an entirely inaccurate and nonsensical description. A more proper description is an "always open gateway" of 5v DC current. If you actually saw a basic block diagram, you wouldn't be saying such nonsense.

The 5V rail is always on. I confirmed by checking with a multimeter when the PSU was "soft off" and "on" with the paper clip test using rivets instead of paper clips.

I wouldn't say it's 'entirely inaccurate', I'd say it's just a simple, very basic and inaccurate way of describing it so as to give a quick picture. I don't think dude would understand a description of '5vsb is just an always open gateway'.

Thanks for the straight answers, /thread. This will help with a project I'm working on that uses a back-up power source.

 

[2is]

Well, internet douchebag,

Pot
Kettle
Black

You're a self proclaimed smart guy, I'm sure you know what that means. More importantly, I'm sure you recognize yourself in it.

 

[Belial88]

Why are you still posting here? Off topic, irrelevant, and just inflammatory.

 

[2is]

You responded to me, I'm responding back. Why are you getting so irritated when you get a dose of your own crappy attitude?

 

[Torn Mind]

I wouldn't say it's 'entirely inaccurate', I'd say it's just a simple, very basic and inaccurate way of describing it so as to give a quick picture. I don't think dude would understand a description of '5vsb is just an always open gateway'.

The hydraulic analogy is commonly used to explain electrical behavior to the layman. An always open gateway makes sense because there is always a little electricity "flowing" on the 5V standby rail. Or, in other words, the circuit is never open.

A PSU-in-a-PSU implies that something in the PSU is converting AC current to DC current within the secondary, which is indeed totally inaccurate, as the current after it goes through the MOSFETS is DC with a little ripple.

Being an computer enthusiast does not make you in any way knowledgeable about electricity, because many computers and their parts do not require any of scientific knowledge behind their crafting to use them.

 

[Belial88]

Whoa slow down there cowboy, I never made any claim about being knowledgeable in electricity (i actually say the opposite in my other thread relevant to this). I seriously doubt that dude, or in general most computer builders, ie people who don't know anything about electricity (as most people in general), would think that psu in a psu analogy means that the 5vsb is converting AC to DC. All they'd think, and really need to know is that it's it's own sub-system. Pretty sure most people, including dude, doesn't know about AC or DC, and I'm pretty sure most people wouldn't understand your 'always open gateway' analogy.

There's a lot of ignorance when it comes to computer components in general, but my explanation was many levels more basic than yours. I don't think most people would understand or appreciate anything you've said so far about how the 5vsb really operates.

But I do <3

 

[Meghan54]

Why are you still posting here?

Same could be asked of you.....ignorant, self-serving, no common sense or courtesy, irrelevant and inflammatory. Or maybe just ignorant (note....ignorance does not mean stupid, retarded, or anything else....just ignorant.)

That will be enough out of all parties. Please stick to the topic and be cordial to each other.
-ViRGE

 

[piasabird]

Some questions like this require the knowledge of an electrical engineer. If a circuit is not connected, does it use power? Maybe the power supply is still using power in the conversion process and uses power to do that creating a ghost load. Just because you have a power supply rated at 650 watts, it does not mean it is using 650 watts. It is like a refrigerator. It has a specific power rating in watts. However, it will use the most power when the compressor motor turns on and the compressor runs.

Similarly a motherboard has a lot of power to unused circuits that are turned on but you don't use them. Unless you have every possible USB device plugged in up to the total number of possible USB devices, then you are not using that much power however, there is some power being used even though you do not have that many items plugged in. The same may go for SATA and other devices and ports on your motherboard. The computer is just sitting there wasting power every day. You may have a serial port or a parallel printer port or a ps2 port or a Firewire port you don't even use. Same thing goes for things like PCIE slots that are empty. They are burning up power sitting there doing nothing. When they are empty they probably don't use much power but some power is being wasted. Sure enough if I plug in a microphone or a USB jack, the computer knows that it is there and will ask me about it so some power is being used to monitor that.

 

[piasabird]

In a way he may be right. Every rail in the power supply usually has a different power rating in amps/watts. I think that some of the pins on the motherboard on the 20+4 main power plug may be for 5v power for things like LED's.

 

[CM Phaedrus]

"A PSU in a PSU" is a fairly accurate way to describe the +5VSB rail of most ATX power supplies. The +5VSB is a separate SMPS. It has its own PWM controller, its own switcher, its own transformer, its own secondary rectifier, and its own filter caps. It is usually a different topology than the main SMPS. The only parts it shares with the main SMPS proper are the EMI filter, bridge rectifier, (sometimes) the secondary supervisor chip, and a few other bibs and bobs.


And to answer the OP, yes the +5VSB is always on as long as the PSU is plugged in and the power switch is flipped to "on".