Quote from: galtbit on January 12, 2014, 03:17:45 AM

Hello: I have had a few power outages in the last few days and would like to buy a UPS.

I have a 1300Waat psu
I spend 900 watts on mining rig.

Do I buy a UPS that handles up to 1300watts or around 900 watts? Any suggestion out there? Thank you for any answers.

It may depend among other things, on the specs of your power supply. Is it Power Factor Corrected Power supply?

As an example:
From: http://www.pcguide.com/ref/power/ext/ups/funcSizing-c.html

Let's say we have a 650 VA UPS. The wattage limit is not specified, so to be safe, we use 60%, which yields a limit of 390W. This means any load we run cannot exceed either 650 VA or 390 W. Some sample power supply loads:
Regular Power Supply, 500 VA Rating: A regular power supply with a rating of 500 VA will run fine on this UPS, because its power factor is probably about 60%, much as the UPS manufacturer assumed (but you should check its specifications, if you can.). Even if the power factor is 70%, that's still 350 W, under the UPS's limit.
Power-Factor-Corrected Power Supply, 500 VA Rating: Some power supplies have circuitry added to them that corrects the power factor to approximately 100% (sometimes called power factor 1). In this case the power supply will have a 500 VA rating and also a 500 W rating. This power supply will overload the UPS we are discussing here because its W rating is too high.

See also: Capacity and Run Time
http://www.pcguide.com/ref/power/ext/ups/funcCapacity-c.html

I hope this helps