Not sure if this was resolved yet or not. But at my company we've experienced similar issues. Had to do with the sine wave that the UPS is built to use. The Intel Server Systems come with
PSUs that require Pure Sine Waveform output from a UPS. Most of the cheaper UPS' do not use Pure Sine waves and instead use a stepped
approximation to one. Both Intel and APC Support confirmed this for us and both are getting lots of reports about it. There is no workaround other than using the
correct type of UPS or no UPS.
APC has two lines of UPS', Back-UPS which uses the stepped waveform, and Smart-UPS which uses Pure Sine Wave. The problem is the difference in price is pretty big.
Hope this helps..