+ 0 Votes Seen this on server... cmiller5400 4 years ago When the UPS did a self test, the server would power down hard. Other servers connected had no issue. Try swapping out the computer's power supply... It may not like the modified sine wave that the UPS generates. + 0 Votes UPS SPC_TCOL 4 years ago That's why we buy at a store that knows that we have some UPS and that there is a high chance that every computer we buy could hang on a UPS, in case that this would happen they would exchange the Power supply without a problem. + 0 Votes Check the line voltage & polarity of outlet InstructorJWN 4 years ago Hi, It is possible that the offices have different "sources" of power and as such, the line voltage may be below the "limit" of the UPS. Anything below 100V is questionable, though some supplys work as low as 90V. It is possible for some reason that the voltage is "too high". Both of these conditions can occur when power is "generated" onsite, in other words, if there is a "sub station" particular to your location (mfg plant, large office building, etc). Problems arise for example if the sub station also supplies power to a large energy consuming device. In a plant environment, something like a punch press, or drop hammer which has a large power consumption followed by a low consumption phase. another in an office buildign may be that you are on the same "sub" as the HVAC systems, and the Air or Heater is causing low voltage. another thing you may want to check is the polarity of the outlet, it is possible that the common and hot wires were incorrectly hooked int he outlet you are pluging in to. You can get small inexpensive electrical outlet testers at many home improvement centers which plug into the wall and can tell you whether the curcuit is working properly. there are also dedicated data loggers which can monitor the voltage at the outlet over time. Hope this helps. Jim + 0 Votes AC Ground TheChas 4 years ago Actually, I find it hard to explain why the UPS works in the first office. Most UPS systems will not switch over to battery if you simply pull the plug. As part of safety circuits, they require at least the AC ground if not the AC neutral connection on the input in order to turn on the output with battery power. Instead of just pulling the plug to test the UPS, plug it into an outlet strip and then switch off the outlet strip. Since most outlet strips only break the hot side connection when you turn them off, the ground and neutral connections are still present and the UPS should switch over to battery. About the only thing that would explain why the UPS works as described in the one office is that you must have an extra ground connection to the PC chassis. Perhaps fully shielded Ethernet cable that is grounded back at the switch or server. Chas + 0 Votes I figured it out soatone 4 years ago To those still following this post or to those who find it in the future, I have discovered what the issue is. While the hardware specs on the computers are exactly the same the power supplies were slightly different. Dell tells me this is because they contract with several different companies to manufacture power supplies for them. The power supply with the issue has a model number of H305P-02. During my testing (I tested several different machines all with different power supply model numbers) I found that ONLY those power supplies with the model number H305P-02 failed when switching to the UPS. All other power supplies work fine. Dell maintains that the power supplies are not the issue; that they are in fact working as designed. Dell states that the power supplies are only rated to work with a UPS that outputs a true sine wave. Since the basic home/office UPS only emulates a sine wave the power supply will not transition properly and simply shuts off. As such technical support was not willing to replace any of the power supplies we had. I did inform them that I had limited the issue to only one specific model of the power supply, but they stated they could not replace it due to the UPS we were using. We did finally get them replaced by going through their sales department.