Computer gets restart automatically in low voltage

[irfanmike]

I have a pc of spec

AMD FX6300
18.5" LED monitor
1TB HD
4GB ram
ATI R7 270 Graphic card
Corsair VS550 PSU
Intex OMEGA 725 600va ups

During night times, mostly around 7pm to 12 pm, there is low voltage in my home. Due to this my system gets restarted automatically when low voltage happens. It gets restart frequently when i am gaming. Sometimes my ups gets to red light and goes off when voltage gets low and sometimes ups gives beep sound for 5 to 10 s but system gets restarted.

Please suggest me some solution. Whether I have to change my UPS or any other. Since my PSU is good, i think i don't need to change it.

 

[popatim]

It sounds like you need a bigger UPS, much bigger.
I'm thinking that the low mains power drains the UPS until it can no longer keep your pc running and then your restart nightmare begins.