|Have you installed the UPS software and a cable from the UPS to the computer? There might be some setting in it's software that may be doing this.|
I'd suspect that the ups isn't providing enough or correct or stable enough voltage and frequency. Some have the pseudo-sine waves that some power supplies don't like.
Might try a true sine wave ups.
The simple test would be to remove plug on UPS side to test.
Usual usp's have a self test and a front panel test button to set a load on battery. It may fail on that test too.
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