When I power down my tower I see all the fans go off, lights too and the sound of it running ceases. It's still plugged into the powerstrip but I powered off and I still see a light on [a green one] on my motherboard that's lit. Should I be concerned about this?
No. It's meant to do that to indicate whether the motherboard is receiving power and whether the system is on or not. The light will probably do something (probably turn red) when you turn the machine on.
Looking over at it now, I see it's still just green.
Yes, it's normal. As is activity on you LAN port's LEDs, if you're connected to a live line.
Bs|Archaon;4017679No. It's meant to do that to indicate whether the motherboard is receiving power...
This is used for troubleshooting purposes. When you are working on the inside of a computer, you want to be sure that there is no charge, so you don't short anything out. So you want that light to be off when working on the computer.
Otherwise, you want it to be on. Which tells you it is working... Unless it starts doing something strange, like blinking, or turning a different color than the normal one(s).