I've seen this before and it's come down to the newer power supplies do not like the less expensive UPS systems.(it's not just HP) These new power supplies can detect fluctuation of 3ms and I've seen the UPS's response times to be from 3-5ms (on the low end). If you want to stay with Eaton try the PowerWare 9130
Best Answer
Here's the service manual you want:
http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c00710498/c00710498.pdf
LED info is on page 91.
According to that, those amber LEDs do indicate faulty FBDIMMS.