My previous Cooler Master PSU died about a month ago and I replaced it with an 850 W XFX Pro Black Edition one as show in my specs. I have had no problems using my PC but sometimes when I shut my PC down the blue Power light does not go out on the front of my tower case and my monitor screen is obviously still receiving a signal as it does not auto-power off as it does normally. I then have to press the Power button on my case to turn off the PC. This does not happen all the time, perhaps once out of six to ten shutdowns but I'm puzzled as to why it is happening at all. It never happened at all with my previous PSU and despite shutting down manually when it happens my PC boots into Windows as normal, without any indication that it has been improperly shut down. Should I be concerned? Does anyone know why this happens? I am using the latest v2004 BIOS for my motherboard and as far I can tell it looks like it is the very last stage of the shut down that is not happening, i.e. the point where the Power LED on the case turns off followed by my monitor when it doesn't receive a signal for 10 seconds.