What is restore on ac power loss?

Restore on AC Power Loss refers to a feature found in power supply units, which is designed to automatically restore computer power when an AC power outage occurs. This feature helps prevent data loss and system crashes that may occur due to power interruptions.

Typically, restore on AC power loss functionality works by saving system state information to non-volatile memory, such as Flash based NVRAM, which retains data even when the power is off. Once power is restored, the power supply unit reads this state information and uses it to turn on the computer, and restore it to the state it was in before the power loss occurred.

This feature is particularly useful for systems or applications that require uninterrupted power, such as servers, industrial control systems, and medical devices that rely on computers.

Restore on AC power loss can be found in various types of power supplies and is often included in several types of backup power systems, such as uninterruptible power supplies (UPS) and line-interactive UPS. Some motherboards also offer this feature in their BIOS settings or through software control.