Question Could power outage harm my PC? i live in a country that we have power outage twice a month at least

Unexpected shutdowns can corrupt windows and damage to components can happen if power turns back on immediately known as a power surge. Should invest in ups system so you have the time to power off properly.
i have power strip with surge protector, is that enough or i need to consider UPS?
 
i have power strip with surge protector, is that enough or i need to consider UPS?

Most of the time, yes, a surge protector is enough. But I've had electronics, including a PC, get trashed from the power cutting on and off, even though they were protected by a surge protector.

UPS's aren't exactly cheap, but they are less costly than they used to be. And, at least for my builds, they're less than the cost of most of the components that are likely to get fried from a bad surge. If i were somewhere with a known unreliable power grid, I'd absolutely budget for one. In fact, since I live in the midwest of the US where thunderstorms and ice storms knock out my power a couple of times a year typically, I have one protecting each of the computers in my house, as well as my nice TV.