apc 750i switch to battery restarts pc

[Anonymous user]

I have recently got an active pfc psu. I called up APC call center and asked which ups i need to go with for 400-450w load, and I am not interested in lots of backup time, allowing me to shutdown is enough. They suggested me apc 750i a pure sinewave ups. I bought it. At load my system take ~360W. At this load if power goes off, my system's off instantaneously and starts again in < 1 sec. This doesnt happen when my system is idles and takes around 180W.
I registered a complaint. They got another 750i and checked with it, same problem. Checked it with another computer , same problem at load > 350. Now if it's rated at 500W, I think it should handle atleast 350W, right? And I checked it with sensitive at low meduim and high , it's the same. When I use it with backups it works, but my psu produces buzzing sound, indicating that it's not pure sinewave. What should I do now? Go with a higher rated ups? Would apc cheange it to a higher rated ups at extra charge? Please help me, it's been over one week I bought ups and I still run my system without backup 😞

[Anonymous user]

Power consumption at load is 380W, measured by powerchute software. I have an assembled system with corsair hx620w, core i7 920 , nvidia gtx 260 benq e2200hd monitor.

[Techie_apc]

The SUA750I can support up to 500 Watts / 750 VA on the battery backup outlets. Please be aware that the size UPS you require depends on the load you plug into the unit. May I know the exact model number of the Computer in question? Is it Customized System or branded System?

If possible, could you please load the Power Chute software to monitor the exact equipment power consumption and the UPS run time?

[Techie_apc]

What is the UPS estimated runtime showing on Power Chute software? What lights are on the front of the UPS when it restarts the Computer? I suspect that the Power Supply is not capable of handling the UPS transfer time. Typical transfer time of the Smart UPS is 4 to 6 ms. Do you have any other branded system? If so, connect it to the UPS and see if the UPS supports it. This will help us to determine the root cause of the issue.

[Anonymous user]

As I have already mentioned I have checked it with another system. coolermaster RP 600W psu. It's not a psu problem as it works well on apc back ups and two computers cant be wrong. backup time remaining is 8 min.

[Techie_apc]

hmm...this is odd issue. What is the model number of the Back UPS that works fine with this System?

I do not think that another replacement SUA750I will fix this issue. My suspicious is that the Server/PC in question is not able to handle the SUA750I transfer time which it takes to transfer from online to onbattery. Could you please double check if your system/PC restarts when the unit transfers from online to on battery? Are you using the Power Chute Business Edition software to monitor the Smart UPS? If you are using it, could you please post the data and event logs which was recorded when this issue occurred?

[Anonymous user]

I have checked it many times, and with different computers. The same result. The only thing whichc matters is load. ANd yes, I am using powerchute to check load. shows 75-80% load and 7-8 minute backups remaining. It works with apc 1kva

[Techie_apc · Accepted solution]

If possible, could you please post the data and event logs of the SUA750I to find out what is going on with it?