My UPS does not work with my new computer

[Anonymous user]

I have an APC Back-Up ES 550.  It has worked great for several years with my old computer -- the computer was maybe 4-5 years old with Windows 7.  I recently got a new computer system running Windows 8.1, and may soon upgrade to 10.  Since the switch to the new system, the UPS doesn't work to keep my computer on when the house power goes out.  I know the UPS is technically working, since all my peripherals stay on [monitors, printer, etc.], and it chirps like it normally does when the power goes out.  But the computer itself turns off immediately, no time for a normal shut-down.  Not good.

I included operating systems above is because I think this issue might be related to Windows 8.1 -- some setting someplace that I don't know about. Or does the OS even make a difference?

Does anyone know what this issue might be, and how to fix it?  The UPS works fine otherwise.

Thanks.

[BillP · Accepted solution]

Hi Kate,

Check to be sure that when you plugged the new system in it is plugged into 1 of the Battery - Surge outlets and not 1 of the surge only outlets. Unfortunately that is a common mistake made with Back-UPS particularly when removing and adding new equipment.

If that is not the case, unplug the computer from the UPS and plug a lamp into the outlet the computer was using and the put the UPS on battery. Verify that the lamp remains on. If it does then the UPS is working properly.

n that case the issue may be with the new computers power supply. When the UPS goes on battery the sign wave changes to step approximated and this could be the cause of the drop. Kbase FA158939 "Computers containing PFC (Power Factor Corrected) power supplies and their use Back-UPS and Smart-UPS SC with Step Approximated Sine waves." discusses this issue.

[Anonymous user]

Ha!  That was it!  I had it plugged into a non-UPS plug, so have now reconfigureded and all seems to be well.  Thanks for the help!