Close to all desktop motherboards have a pin header that is supposed to power an LED on the front of an enclosure with to indicate that the computer is on. In the documentation for my board, these pins are described as "Power LED Signal anode (+)" and "Power LED Signal cathode (-)".
This made me curious and by measuring both pins with a multimeter seperately, I found out that the anode on the board is always supplied with 5V (compared to GND) as long as the PSU is connected to AC current while the cathode is supplied with 5V normally and gets pulled down to ground potential when the PC is turned on.
What I would've expected was the cathode being connected to GND directly and the anode being pulled down normally and pulled up to 5V when the PC turned on.
Is there a good reason why the manufacturer would choose to do this? Is there any advantage in powering a LED this way over the way I described? Is this probably even common practice with desktop mainboards?