Motherboard LED stays on even when PC unplugged

The green PB_PWR LED on my motherboard stays on even when I shut off the power supply switch and unplug my PC completely from the wall. The light stayed on for over an hour before finally turning off. Is this normal? What kind of phantom power could be causing this?

I even tried shutting off the PC, unplugging it from the wall, and unplugging the 24pin power connector to the motherboard, and the light stayed on.

The computer seems to boot normally otherwise.

mobo: Asus P7H57D-V EVO
PSU: Corsair AX850 (850 W)
vid: eVGA GTX460 768 MB
RAM: Corsair 4 GB DDR3
HD: WD Caviar Black 640 GB
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  1. That should have said "SB_PWR LED", not PB_PWR LED. Also, sorry for the double post, not sure what happened.
  2. Yes, it's normal. There are capacitors on the board.

    I have found that you can extinguish these lights by unplugging the power supply and then turning on the power switch. This drains the caps. But don't go licking your motherboard even if it's removed from the case; one of the caps might bite you.
  3. No problem then. I've had a similar issue with some other brands. May have to do with the motherboard battery or a bios setting. I wouldn't worry about it. IF you fiddle with the power supply leads, you are liable to create a real problem. I would leave them alone.
  4. This next topics has been merged by Mousemonkey
    Motherboard LED stays on even when PC unplugged
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