Why does my Windows PC turn itself on at the same time every day?

After upgrading from Windows 7 to Windows 8 a few weeks ago, I found that my PC would power up from Hibernation at 12:53pm (precisely) every day. Eventually it turned out that a Scheduled Task called mcupdate_scheduled ("Check for Media Center updates") had the flag "Wake the computer to run this task". This is the issue described in this KB article from Microsoft - unfortunately this type of article is only easy to find if you know the magic keyword "mcupdate_scheduled" already...

Interestingly, Media Center and the mcupdate.exe executable had been removed in the upgrade to Windows 8, so the task had become useless anyway and failed with error 0x80070002. Disabling the task fixed the power-up problem. It should be noted that the "Wake the computer to run this task" setting overrides the global option "Sleep" > "Allow wake timers" under "Advanced power plan settings" for the current plan.

Update: There seem to be other "system maintenance" jobs that can also make a Windows 8 PC power itself up for things like installing updates. I am still trying to collect a more complete list here...