Battery backup is overloaded

[Ytterbium]

I ran my GPU and CPU at full load and this draws more that the 865 W that my Back UPS Pro 1500 can provide.

What happens at this point? will it provide the 1000 W that the computer needs?

If I got the APC Back-UPS Pro External Battery Pack, this would increase the run time but does it help with the overlaoded?

[Teken]

You'll need to invest in a larger UPS that meets your power requirements. As the UPS is rated at 80% duty cycle of use so over loading the UPS can result in problems. The external battery pack will not offer anymore power but will extend the operational runtime.

Unlike many fuel based generators a UPS rarely if ever offers any meaningful surge current capability. You'll note APC does not indicate or specify any metrics in their literature that state these phrases: Inrush, startup, power boost, etc. Regardless, depending upon invertor design you can run it to its maximum and see the real world results.

If history is any indicator you'll either start to hear beeping and LCD messages. If that's all you see you can do whatever you like. If the UPS disconnects the load from the outlet you know what happens. If the UPS turns off completely after doing all manner of beeping and LCD blinking - You know!