This is why a lot of ATX motherboard designs suck. Did you know that plugging in a PCI card while your ATX based machine is plugged in can fry the motherboard? Why? Simple. Modern Wake-on-lan setups actually supply the standby power to the ethernet card via the PCI slot. Yup! Your PCI slot has a 5V line active all the time, even when the power is off.

This has led to mommyboard makers putting LED's on the board to warn you to unplug it before putting in cards. This is fine and dandy, but I miss the days of AT boards, when you could simply turn off the power and plug in your cards. Since your machine is still plugged in, the machine's frame is grounded and the chance of damage due to ESD is reduced.

Of course, designing proper ATX motherboards shouldn't be that big a deal! Let's keep PCI slots unpowered when the machine is off. In fact, the only place on the board where there should be power is the area around the ATX power connector, where the power switch and wake-on-lan headers are located.