ASROCK IMB-151 User Manual page 27

Deep S5
Mobile platforms support Deep S5 in DC only and desktop platforms sup-
port Deep S5 in AC only. The default value is [Disabled].
Restore on AC/Power Loss
This allows you to set the power state after an unexpected AC/power loss.
If [Power Off] is selected, the AC/power remains off when the power
recovers. If [Power On] is selected, the AC/power resumes and the
system starts to boot up when the power recovers. If [LAST STATE] is
selected, the AC/power restores to the last power state when the power
recovers.
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