Apparently yes if your psu has Active PFC.
As far as i'm concerned it would have to be a worst case scenario though.
You'd have to be relying on the ups constantly and running the pc till the battery drains.
I have a simulated sine-wave ups and i'm not concerned in the least.
The ups has kicked in twice in the last year and a half for maybe a second or two each time before power was restored.
I think it's a none issue.
Some have argued that an UPS may in some cases demage the PSU. ...
Basically there are 3 kind of waveform in the UPS:
1- square wave
2- quasi-sine wave pulse width modulated stepped rectangular waves
3- sine wave
Quasi sine waves and square wave outputs may even be harmful to small electric motors and power strip protectors. But all three are ideal perfect for all electronics. Because all electronics are so robust as to make any UPS output irrelevant.
Same reasons why most all 'so called' surges are made irrelevant by protection already inside electronics.
Anything a UPS might do to create a pure sine wave is completely undone by how electronic power supplies operate. Therefore a nearly $1000 UPS provides no useful function for so much more money. But are promoted by subjective rationalization.
As Davcon notes, a UPS output can be so dirty as to confuse PFC circuits inside some newer supplies. This is not and could not be destructive. Simply causes the power supply to see a loss of AC power. When a particularly 'dirty' UPS switches to battery, then a computer's supply may become confused.
That is significant. A UPS not in battery backup mode is some of the cleanest power seen by the load (ie computer). Often not understood when knowledge comes from hearsay. To discover if a UPS output is too dirty, unplug the UPS. Simulate a power failure. So that dirtiest power seen by any computer is generated by a UPS in battery backup mode. To learn if that 'dirty' power confuses a PFC circuit.