Who is powering Wake-On-LAN capable card?

Question

Who is powering Wake-On-LAN capable card? Is this PSU? If it is then, where are these wires on PSU, where I can take powed in power off mode?

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The focus is on details of power source. There is no such details in cited answer.

Answer 1

From Wikipedia about ATX:

+5 V_SB (+5 V standby) supplies power even when the rest of the supply wire lines are off. This can be used to power the circuitry that controls the power-on signal.

+5 V_SB is the purple cable. To connect a device (e.g. a small bulb) you need two cables, the other one would be black GND.

ATX Specification, Version 2.2 from about 2003-2004 includes the following:

4.1.3.2 5VSB

5VSB is a standby voltage that may be used to power circuits that require power input during the powereddown state of the power rails. This power may be used to operate circuits such as soft power control. It is recommended that the 5VSB line be capable of delivering 2 A. This current allows the implementation of features such as Wake on LAN technology in accordance with IAPC (...).

2 A is recommended, not strictly required; but I also found this Intel guide from 1998. It mentions the minimum of 720 mA. This minimum translates to 3.6 W of power, 2 A would give you 10 W. I think it's reasonable to expect you can get at least 3 W, unless the PSU is very old or poor or faulty.