QUOTE(adala @ Dec 2 2019, 09:58 PM)
Thank you all for you feedback and advice.
Either I have to buy a higher power UPS or change my PSU to a lower power.
My PC is new together with the UPS. Bought in June.
The supplier didn't calculate and choose the UPS power output properly to suit the PSU.
When buy a UPS, 1st spec need to know is how much power need to backup your device.
Ex- PSU - 650W. Monitor - 120w. Total is 770w. Than add in some allowance for safety. 20-30%.
You need a UPS that can give 770Wx30% = 1000W.
It is not the battery in the UPS that give 1000W. But the inverter that converts DC12v to AC240V in the UPS is capable to run at 1000W.
So your UPS 650VA will shut down for safety if draws more than 375w. If not, the UPS will burn down.
2nd is the battery in the UPS. The battery gives the duration it can backup. The bigger the battery, the longer is can backup.
So to get a UPS, 2 spec need to check.
1) VA - the watt it can output
2) Time - Duration it can backup run at specific watt.