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A desktop PC can often turn itself on when electricity returns if its BIOS or UEFI supports an AC power-recovery setting. This restores power to the machine. Recovering unsaved work and restarting the applications you need require separate planning.
Find the AC power-recovery option in BIOS or UEFI
Read the manual for your exact motherboard or computer model. Manufacturers use names such as Restore AC Power Loss or AC Recovery, and the menu location varies. Not every computer, particularly a laptop with its own battery behavior, offers the same feature.
Enter firmware setup using the key or method documented by the PC vendor. In the ASUS ROG MAXIMUS Z790 HERO example, ASUS places the setting under Advanced > APM Configuration > Restore AC Power Loss. The official ASUS instructions explain that model’s options and power-loss detection conditions. Treat the path as an example, rather than a menu shared by all boards.
| Typical option | Behavior when AC power returns | When it may fit |
|---|---|---|
| Power Off | The PC stays off. | You want to restart it manually. |
| Power On | The PC powers on after the firmware detects the loss and restoration of AC power. | A supported unattended PC needs to start when electricity returns. |
| Last State | The PC follows the power state recorded before AC power was lost. | A machine that was intentionally off should stay off. |
For automatic startup after a detected outage, choose the supported Power On option and save the setting. A Fast Boot or Normal Boot choice can concern how startup proceeds afterward. It does not universally enable AC power recovery.
Test the behavior without interrupting live work
Save files and close applications before testing. Follow the vendor’s procedure and allow for any specified delay while standby power disappears. Avoid pulling power from a running PC merely to test this setting. Where possible, test the Power On choice after a clean shutdown, then remove and restore AC power as the manual directs.
If you chose Last State, a test performed after a clean shutdown may correctly leave the machine off. That does not show the feature is broken. Test only the behavior supported by the manual and record which setting you used.
If the PC does not start, check the saved setting, the PSU’s switch and the availability of AC power. A very brief interruption may not meet a particular board’s power-loss detection conditions. A UPS can also keep standby power present, so the motherboard may not see an AC loss even if the wall supply briefly fails.
Separate power-on, Windows startup and app recovery
There are several stages to an unattended restart:
- The firmware switches the computer on.
- The operating system boots, possibly stopping for a recovery prompt or error.
- The required service or application starts under its configured account.
- The application resumes work only if it supports recovering or restarting that task.
A Windows Startup app normally runs after its user signs in. A properly configured background service can operate without a desktop sign-in. Do not enable automatic sign-in solely to make a generic restart checklist work. Choose the startup method supported by the application and retain the account’s security controls.
For a newly installed Windows PC, use the setup checklist to verify updates, drivers, startup apps and security before relying on unattended operation. If drive encryption uses a startup PIN or USB key, that authentication requirement also needs to be considered. Our BitLocker guide explains the difference between normal unlock and recovery credentials.
Keep recovery checks and protect your files
A power cut removes the contents of ordinary RAM. This BIOS option cannot recreate unsaved documents or guarantee that a long-running task continues from its previous point. Enable the application’s own save or checkpoint features where available.
Keep independent backups and test that you can restore them. The existing backup-software guide provides examples of backup tools. A suitably configured UPS can provide time for a controlled shutdown, but its runtime and shutdown behavior depend on the equipment and configuration.
Do not suppress Windows recovery checks with a generic boot-status command to promise an always-running PC. If Windows stops at a recovery screen after an outage, investigate the underlying problem using Microsoft‘s Startup Repair guidance. Automatic power-on is useful only when the rest of the startup and recovery process also works.