Question Computer restarts (sometimes) from AC loss even with a UPS?

[torveo]

I have an EVGA SuperNOVA NEX650G 650Watt PSU in my PC which is (supposed to be) backed by a Cyberpower CP1000PFCLCD Pure Sinewave UPS. But it still restarts sometimes when AC drops. The thing is, this is my second try with this UPS. I had to RMA the first one because it would randomly reboot my PC for no apparent reason. I really don't want to do it again...

According to the cyberpower website, the UPS has a transfer time of 4ms. Is that really not fast enough for this PSU? My system power draw is 381 watts max at the outlet(That was the max ever logged on a watt meter that was connected for a week, and also during simultaneous GPU and CPU stress tests), so its well within the 600 watt limit of the UPS, and its not like the PSU is being run at its limit causing the capacitors to drain faster and tank the hold-up time.

Also, it never seems to happen when I pull the plug on the UPS. It switches over no problem and my PC keeps running, happy as can be. Its only when a real AC power event happens that it reboots.

Im not even sure what do to at this point. I paid $180CAD for a UPS that only works 75% of the time. : /

 

[Metal Messiah.]

According to the cyberpower website, the UPS has a transfer time of 4ms. Is that really not fast enough for this PSU?

Yes, that should be enough for your current PSU, IMO. I don't have that much experience with regards to UPS, so I can't really comment on the current situation, which you are facing though.

 

[torveo]

I thought for sure it would have been fast enough as well. Thanks for your input though. Any at all is appreciated.

Another strange thing that I forgot to mention, is that the PC shuts off completely(All LEDs+fans are off), then about half a second later it all comes back on. Which is eerily similar to what happens when you change certain motherboard settings, like power delivery and clock rate settings. I wonder if maybe, just maybe, its some sort of finicky protection on the motherboard causing this? I noticed some people talking about built in surge protection causing issues with UPS's on an ASUS motherboard. I don't have that one though. Mine is an MSI Z97-G45.

 

[Satan-IR]

I think the UPS is capable of providing the system with the necessary power, hence, the restart. If there wasn't enought power the system would shut down.

Motherboard surge protection kicking in (if applicable) should be unlikely because a decent UPS inherently should not create a surge in the first place.

If that's a line-interactive UPS the transfer time shouldn't be an issue but it seems it is, hence, the restart.

 

[torveo]

So I did some testing and research, and it seems that the UPS cannot handle anything over 200 watts. Which would be normal albeit a little cheap if this was a 300 watt UPS.... Except Its not... Its a 1000VA/600W model. From what I can tell, it seems like other people are having the same issues with this too. I guess my $180 is stuck going towards a UPS that will only protect me while web browsing now. A refund is out of the question as the date of purchase was last year, and naïve me assumed the replacement I got would have worked as advertised.

Since the first UPS I RMA'd and the one they sent back both do the same thing at 65% load, Im just going to assume its shoddy manufacturing and bloated specs. They cant really expect me to buy a 1850 watt unit just to be able to not have it shutdown at 400-ish watts, can they? Sheesh. Shoulda went with Tripplite or APC or eaton or something.