we don't have any electrical problem that often on our place but seeing as my husband spends lot's of money on building different systems for different usage i really suggested to buy some UPS which should help out to not damage our system in a small chance of it happening.
Like many people say "Better be safe than Sorry"
I would like to stay on the APC brand as it's the only one available to where we live.
With the 3 monitor setup running 120~150W you wouldn't expect the UPS above to handle the load unless that PC happened to be in near idle mode with home office like workload, surfing the web, etc. Taking 2 monitors off the UPS should let it handle any load except gaming.
The 1100VA model has a good chance of holding up briefly under a gaming load if only 1 monitor is plugged into the battery (and it's the monitor where you can shut down the system).
I would recommend a model with a true sinewave output, such as http://www.apc.com/products/resource/include/techspec_i... (or the larger one). Your PSU may see the stepped approximation of a sinewave as bad power, and shut off, even though the UPS is working. I have personally experienced this issue, but a sinewave UPS (another APC model, don't remember exactly, but was 115V) took care of the problem. You might check with Corsair and/or APC for specific details concerning your model of PSU.