Does this by any chance occur only when hitting end turn?

I don't suppose you have a Kill-a-watt handy?  I'd be interested in seeing how much power your computer, likely the gpu, is drawing when the game runs.  Esp since you have a 750VA ups.

Later,
LAR 

If it's a UPS that runs through the battery at all times rather than switching from line power to battery only in a power outage, that's probably why. No UPS I've ever seen that was designed for home use can cope with a current-gen SLI setup at full tilt on battery.

You could try turning the graphics settings down too.  I'm not 100% sure at what point the problem's beginning, but it should help once you're actually playing.  

Another solution, if you can do this in Crossfire (nVidia man myself), is disable one of the graphics cards when playing Elemental. That should drop your power draw by enough so your UPS is happy.  

Other than that, all I can say is the normal "this is a beta and because it's still in development it's not going to be optimized to run efficiently on your computer."

Later,
LAR