Why does my PC restart on power restoration while connected with power inverter?

Inverter Specifications:

  • Luminous Evo 1550 (pure sine wave inverter)

PC Specifications:

  • Intel Core i5-12400F CPU.
  • 16 GB Dual-Channel DDR4 RAM.
  • Gigabyte B660M DS3H AX DDR4 Motherboard.
  • Nvidia GeForce RTX 3060 Ti (8 GB) GPU.
  • Corsair VS650 PSU.
  • LG UltraGear 1080p 144Hz monitor

A few things to note:

  • The PC is already connected to the inverter. The inverter is set to UPS mode and is approximately 7 months old.
  • The restart happens only when mains power is restored, not during the power outage itself.
  • No major appliances are connected to the inverter. The only other connected device is a TV, which is usually turned off while I’m gaming.
  • The issue occurs regardless of the game — both lightweight indie titles and demanding AAA games trigger the same behavior.