System Standby Isn't "Standby"

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I just recently built my new computer. Standby worked perfectly fine. But after having it for a week or two, the system does a very strange thing. It goes into standby, but all the fans are still running, I know it's in standby because I hear the hard drive shut off and USB devices are temporarily disabled (the lights on my wireless Logitech Keyboard and mouse's HUB shut off). Anyway, I did somethin bad at one point and ended up re-formatting my computer. It suddenly went into standby fine with all fans off and everything, but did the same thing after a few weeks. I tried logging off and using standby there, just in case it was a process I had running that kept it from a proper standby, but that didn't work either. Maybe one of you folks knows what the hell I'm missing? Any help is appreciated, and thanks.

 

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Alright, the problem with the entire system powering down has been fixed. However, I have a Logitech cordless MX Duo. It apparently isn't able to wake my PC up from standby (it has before). I checked the BIOS, and "Wake up from S3 by USB Keyboard" is enabled. Anyone have a clue why it's not workin? I checked, and no USB devices are even powered. I'll keep working on it, but if anyone has anything, thanks for the help.