I've been struggling with trying to figure out why our new Dell Optiplex 780s can't be remotely powered on using Wake-On-Lan. In order to make this work, you need make the following changes in the BIOS:
- Internal NIC must be enabled with PXE (this was the gotcha!)
- Enable Low Power Mode should be unchecked
- Remote Wakeup needs to be set to enabled
The kicker was realizing that the Internal NIC needed to be enabled with PXE. Prior to adjusting that setting, everything looked ok, and WOL worked to wake computers from sleep, but I couldn't remotely power them on.
In order to save power, we turn try to turn off our instructional lab machines when they're not in use. Because some of our labs are open on weekends, some are open every day, and schedules change during the summer and semester breaks, we try to adjust this and keep the machines off when not in use. I have scripts that power on each room as a Windows scheduled task.