PSU/UPS issues

[MedicBoi]

I just bought a Cyberpower CP1500AVRLCD UPS as the place I just moved to seems to have some power issues somewhat regularly. After setting it up and testing it, I found my computer shuts off when it switched to battery power, and even when running on battery it won't boot at all. Sometimes it will attempt to turn on for about a second before shutting off again. The PSU I have is a thermaltake toughpower grand RGB 750W. I don't believe the UPS is being overloaded because even at full load, with monitors and whatnot the UPS only shows about 500W being pulled and its rated for 900W. My guess is the PSU just does not like the power being provided from the UPS despite it showing an output of 120V and 60Hz. At this point it seems I'd either have to replace the PSU in hopes for one that works on this UPS, or replace the UPS with a pure sine wave output. Any suggestions would be great!

 

Also I tried turning on dummy power in the BIOS which seemed to almost help, but not quite. The attached video is the behavior when switching to battery power with the dummy power turned on (when disabled it shuts down and doesn't even attempt to boot.)

Edited July 31, 2021 by MedicBoi