What UPS do i need?

Yes, it would have to otherwise how can the PSU still supply power? It has to come from somewhere. Sorry to hear about the power issues, I've been lucky enough to only need surge bars. Out of curiosity, where are you?

There may be another issue, most UPS sold are not properly functional with a (750w) PSU that has active PFC.
Actually from what I've read any power supply with active PFC requires a UPS with a pure sinewave and those are considerably more expensive.
Only repeating what I've read, it's easy to determine if you have active PFC though, there won't be any 115/230 volt switch on the power supply.

living in rural Ontario Canada

Hi - this is Jonah Cagley from CyberPower Systems. I recently read this thread and wanted to let you know that CyberPower has recently launched a new UPS line that supports equipment with Active PFC power supplies and standard (or conventional) power supplies. The new UPS line is called Adaptive Sinewave UPS. It's available in both Desktop tower and Rackmount/Tower models. Our new waveform design not only supports Active PFC power supplies but it is the most affordable UPS solution in in the market for this critical compatibility issue.

Depending on the model you require, you can save up to 50% compared to pure sine wave. I encourage you to visit http://www.cyberpowersystems.com/about-us/news/adaptive... to learn more and check it out for yourself. Please let us know your feedback when you have a chance. We'd love to hear from you.

Best regards,
Jonah

why not use

wall outlet <- Car Batter Charger <- Car Battery <- DC to AC Inverter <- Surge protector or Good AVR <- PC