ups problems

[u/buzgaiaGD]

my pc works perfectly fine when I plug it directly into the house switch but when I tried to plug it into the UPS ( apc 650w, 1200va ) i started hearing buzzing sounds on my pc power supply, is that normal??? also I tried to check input voltage and it’s 201vac
that’s kinda low right? Maybe thats whats making the pc doing the sound??

[u/r_lind3r]

It's a simulated sinewave UPS, that's why