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using 5V SB for my project

Printed From: ASRock.com
Category: Technical Support
Forum Name: Intel Motherboards
Forum Description: Question about ASRock Intel Motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=4394
Printed Date: 05 Feb 2025 at 5:56pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com


Topic: using 5V SB for my project
Posted By: kappi1997
Subject: using 5V SB for my project
Date Posted: 11 Feb 2017 at 2:04am
Dear Comunity
I need to supply my mikrocontrollersystem with current while my pc isn't running. So i saw that there is a 5v SB pin on the Mainboard(asrock x79 extreme 3) at the header for the IR sensor. Now i wanted to ask if it is possible to pull current from there withouth any authentification or something like that. My board could have peaks of 1 Amp but normaly uses around 200mA. Is this a problem?(my power supply could deliver enough current on 5Vsb). The part of the Manual:




Replies:
Posted By: wardog
Date Posted: 11 Feb 2017 at 2:19am
" rel="nofollow - Why there? Just take it from the PSU and not worry of draw.


Posted By: kappi1997
Date Posted: 11 Feb 2017 at 5:01am
the thing is i don't want to modify my psu cause it would waste my warranty.


Posted By: wardog
Date Posted: 11 Feb 2017 at 7:37am
" rel="nofollow -
Originally posted by kappi1997 kappi1997 wrote:

the thing is i don't want to modify my psu cause it would waste my warranty.


I don't think you'd need to open it. +5v is +5v

If you "expect' the +5vSB to be hot, the computer must be in a Sleep State anyway.

It would seem to me seeings the PSU is supplying +5v to the SB "rail' you could simply grab a +5v you need from the red wire off a 4-pin molex from the PSU.

Meh, that might not workout above to grab a +5v supply ............. sec



Tada. Use a DVM to verify but use the purple wire in position 9 of the main 24-pin motherboard power. That's the +5vSB wire coming directly from the PSU.

http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain24



That work? Or didn't you plan on having to have the computer in a sleep state?





Posted By: wardog
Date Posted: 11 Feb 2017 at 8:06am
Originally posted by wardog wardog wrote:

Tada. Use a DVM to verify but use the purple wire in position 9 of the main 24-pin motherboard power. That's the +5vSB wire coming directly from the PSU.


We learn something every day.

That line above. Mea Culpa. That's the VSB line, which is always hot. Sleep or powered off.



Posted By: parsec
Date Posted: 11 Feb 2017 at 9:31am
" rel="nofollow - An alternative to the IR header might be a USB port. The USB ports have been powered up after the PC is shutdown on ASRock boards for a while now. Your board has the XFast Charger port on the IO panel, and in one of the USB 2.0 headers on the board, which could be adapted for your purpose.

See page 33 of the User Manual, which you must download from your board's information page:

http://www.asrock.com/mb/Intel/X79%20Extreme3/?cat=Manual

Your board also has a USB 3.0 header on the board. USB 3.0 provides more current that USB 2.0 does.

I am skeptical that the +5VSB pin on the IR header can supply up to 1 Amp of current, and as said above, you would need to be in Sleep or Hibernate mode for the +5VSB supply in your PSU to be active. Of course even when shutdown, a board still receives power from the PSU.

But consider this: If the PC can be turned on and off from the IR remote control, is it just in Sleep, or really shutdown?


-------------
http://valid.x86.fr/48rujh" rel="nofollow">


Posted By: wardog
Date Posted: 11 Feb 2017 at 10:30am
Aw hell. I didn't even think of using a USB's +5v.

Even sick you still have it. Thumbs Up


Posted By: kappi1997
Date Posted: 11 Feb 2017 at 6:58pm
First Thank you for all your helpfull answers. So i know from tests that the 5v sb is always on but you are right probably it isn't meant to pull current from this part of the board. So did i understand this right you would recommend me using the usbpwr pin from a usb2.0 port?(usb3.0 is in use)Doesn't usb power need a verification so it delivers more than 500mA?



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