I think you are looking for a monitoring tool.
BigFix will tell you how long a server has been unresponsive (offline, hung etc)… assuming the BESclient is not in a degraded state… but it’s not going to tell you how long the server has been offline over the past day/week/month.
I suppose you could check the BigFix API on a regular basis and record that information, but then you are basically developing your own rudimentary monitoring tool.
If Jason is saying this is in PowerMgmt, I was not aware. I may have to evaluate that feature further then myself