Shut down idle computers on your network automatically (IBM developerWorks)

I would think that this being an article on networks, it would make more sense to keep one computer running and have that sort out the timing, rather than rely on each client's BIOS to do the right thing at the right time with any synchronicity, through power failures, etc. Some BIOS don't even have this option, or it's buggy, or it fails to take account of Daylight Savings, or it just doesn't work at all, or it's inflexible. And what if you *need* to wake up the stations at an previously unscheduled time? You're falling back on WOL or manual intervention anyway.

Personally, I use WOL with a central server in the school I work in. It has it's /etc/ethers filled out and a script to sort out groups of computers (e.g. wake up classrooms, wake up ICT Suite, wake up office machines, etc.).

The client computers (including a couple of Linux servers which do filtering/caching/etc.) shut down when the last user logs off or it hits a certain time (some idiot always leaves one logged on for no reason). In the morning, I can wake the entire ICT Suite or similar with a scheduled task fired off by either a Linux or Windows server, depending on what it's being woken up for. I can also just run the same script at any time if there's an unscheduled class that wants to use them quickly or if there's been a power problem that has resolved itself. The computer running the flashy LCD display at the front of the school comes up and down on its own schedule using WOL fired off by the same servers.

Cron jobs, scripts and WOL - it's the best solution I've found. With suitable fiddling, I've even had the computers boot up each night when the server has switched into "maintenance" mode - they boot off the network, where the PXE boots into a special boot disk (only between scheduled hours etc.) which does some maintenance/testing on the machines and could even rebuild the entire machine from scratch, they then shutdown and the server switches back into normal mode just before the day starts in order to continue operation as normal.

The only problem I have with that is the cleaners who love to switch stuff off and unplug it but that's just a universal bane of IT anyway...