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I want to integrate a RaspberryPi into the case of my desktop PC, that has an ATX-PSU. I want the RaspberryPi to keep running, even if the PC is shut down. It would be nice to avoid the additional cable from outside the case to supply the RaspberryPi. So, is it possible to use the +5VSB to supply the RaspberryPi and the PC in parallel? It should work supposed the PSU delivers enough power via +5VSB, right?

I thought of using something similar to this, but without PS_ON: http://www.amazon.de/Aqua-Computer-Connect-24pin-Standby-Aquaero/dp/B002BX05CM

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Read the label on the PSU box. It should say the maximum rating of +5VSB. It is probably 2-3A. So that should be enough for Raspberry Pi assuming it needs max. 1.5A and the rest remains for motherboard.

Why do you need that cable? +5VSB is on no matter if your PC is off.

That cable either allows you turn on the PSU from an external device, bypassing motherboard commands or allows you to monitor motherboard power on status.

The green wire of an ATX connector is called PS_ON and when connected to GND turns on the PSU (is active low). That doesn't affect +5VSB which is always on. On older PSUs this voltage was taken from a linear transformer, totally unrelated to the SMPS that supplies the rest of the voltages.

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  • \$\begingroup\$ Thank you! Yes, I know about the PS_ON connector. The cable I linked to is not exactly what I need, I should have been more clear about that. But if I am correct, the cable is used to supply the controller of a aqua cooling, with +5VSB and GND. Additionaly, it provides PS_ON, to give it the possibility to turn the PSU off. Except for the PS_ON and the fact that I need an USB-plug, this is pretty much what I need, to supply the Raspberry Pi. \$\endgroup\$ – Marcel Meyer Apr 21 '14 at 20:32
  • \$\begingroup\$ Did you opened the PC box to read label on PSU? Just in case. For example I have an old PSU that is rated at 110W and has +5VSB @ 2A. It's a good idea to check the user manual of your motherboard maybe you'll find how much power it needs when in standby. \$\endgroup\$ – Cornelius Apr 21 '14 at 20:34
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    \$\begingroup\$ Yes, should be fine, it says 3A. \$\endgroup\$ – Marcel Meyer Apr 21 '14 at 20:39

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