I'm researching the D945GCCR intel motherboard, and the manual says this:
For LAN wake capabilities, the +5 V standby line for the power supply must be capable of providing adequate +5 V standby current. Failure to provide adequate standby current when implementing LAN wake capabilities can damage the power supply.
I just did a search on this subject: "+5 V standby current power supply", but actually a better search term is "5VSB":
ATX Power Supply Power-On Switch - this page is actually very helpful! It explains how the power on switch works.
Finally found the wikipedia page on power supplies, which had these helpful tables:
| Color | Signal | Pin | Pin | Signal | Color |
|---|---|---|---|---|---|
| +3.3 V | 1 | 13 | +3.3 V sense | ||
| +3.3 V | 2 | 14 | -12 V | ||
| Ground | 3 | 15 | Ground | ||
| +5 V | 4 | 16 | Power on | ||
| Ground | 5 | 17 | Ground | ||
| +5 V | 6 | 18 | Ground | ||
| Ground | 7 | 19 | Ground | ||
| Power good | 8 | 20 | -5 V | ||
| +5 V standby | 9 | 21 | +5 V | ||
| +12 V | 10 | 22 | +5 V | ||
| +12 V | 11 | 23 | +5 V | ||
| +3.3 V | 12 | 24 | Ground |
Also found this interesting but unrelated page:
How to Convert a Computer ATX Power Supply to a Lab Power Supply