I know I have numerous posts up, but I didn't want to mix the questions on the same thread. I hope that is okay.. I have an M3n78 PRO mobo, and it does have a green indicator light to show that power is on or being supplied to the motherboard. The light is always on, as long as the PSU's switch is flipped on. Okay, tonight I was testing Memory by plugging it into different memory slots. I had 2 sticks to test. My normal procedure was to power down the PC and flip the power switch on the PSU itself. On a few occasions I forgot to flip the power switch, but I did ensure the PC itself was "off," and I just replaced the memory or reseated it as necessary. On retrospect, now I'm worried forgetting to flip the PSU switch would cause a shortage or some electrical problem somewhere. My question, is this something to worry 'bout? or am safe by the fact that the PC was turned off (just not powered off from the PSU)?