If the bulbs do not blink in this room, the TV works fine, etc. - it is unlikely that this power supply and UPS is not needed.
I had a similar situation
helped me power stabilizer.
Now about this:
3,000 W redundant, of course. Can that easier.
I wanted it with a bypass, and less powerful with a by-pass was not in the store.
A cheap UPS is even worse than stabilisator.
P. P. S.:
But it is in a that you have a working computer power supply,
works fine cooling the computer
not "swollen" capacitors on the motherboard