MacOS – How to know if (and when) a shutdown occurred due to power outage

The original G4 Xserve was prone to structural 'sagging' after spending a while in a rack. I'm not aware of any specific fix for this problem, which causes random kernel panics / shut-downs / other weirdness; later model XServes were not affected (not sure when exactly, but I've never seen this on any intel xserves, while I did see it on a significant number of g4 serves).

http://tidbits.com/article/11735

Sorry for the bummer news :/ If you can get your hands on a late-model intel xserve, they still hold up pretty well. I use several of them on a regular basis.

As you have seen, all Apple products actually run even when you power them off. On iOS, the battery keeps time and on Macs, the SMC is responsible for knowing when the power button is pressed and if the Mac should start itself up due to a scheduled wake or power on being saved in the NVRAM.

If you called for service, Apple would likely focus on several things:

1. Have you checked that the firmware and software is up to date.
2. Does this happen every single time, or is it an occasional thing.
3. Have you disconnected everything (including the mouse and keyboard) and tested to see if it's in any way related to a peripheral.

Assuming you can reproduce this at will (it happens every time), you would probably take steps to reset the SMC to ensure it's getting proper readings from the temperature sensors.

• Intel-based Macs: Resetting the System Management Controller (SMC)

If after spending the 10 minutes it would take to read through each and every step (I feel it's important to perform the steps in order - even if they seem unrelated or unnecessary), I would expect them to want to run diagnostics to physically open the Mac to check the sensors and wiring. Your symptoms sure sounds like the SMC either is stuck in some loop and not reading the temp sensors. Failure to control the fans properly could also be a hardware issue where the SMC is receiving a signal where the correct action is to keep the fans not only spinning, but spinning at an elevated level.