how long can a 600va ups last in this pc?

[stingbee]

Ups model: apc bx600 ci-in (600va 360w)
I need the ups to withstand just over a minute or two so that I can shutdown my pc. I have i5 2500k processor, will buy msi r9 270x 2gb graphics card, seasonic 520w psu and wd caviar 500 gb HDD, 8gb ram, 21 or 20 (not sure) inch lcd monitor from Samsung.
Also, Does using UPS have any effect on the computer rather than connecting it directly to the wall? ( like not proper power being supplied to psu?)
And finally, I have a pretty compact cabinet with wire connection congested inside. I heard msi r9 270 Is a big card. Will it fit in? ( used hd 5750 which was quite small)

 

[kanewolf]

A good UPS will have a method to signal the PC, usually USB so that a shutdown can be started automatically before the battery is exhausted.
The best way to determine runtime would be to measure the power usage and then use the estimators that the UPS manufacturers have.
But, you should get a couple min from that size UPS.

 

[ko888]

APC BX600CI-IN
Output Waveform Type on Battery: Stepped approximation to a sinewave

That Seasonic 520W PSU will be incompatible with a UPS that outputs a stepped approximation to a sinewave. The UPS will fail to switch over to battery backup mode during a power interruption event.

X-bit laboratories reviewed the Seasonic S12-II 520 and tested UPS compatibility with an APC SmartUPS SC 620 that outputs a stepped approximation to a sinewave.

I could not make the S12-II 520 stable as it would shut down even at a load of 300 watts when the UPS switched to its batteries.

Run time graph of APC BX600CI-IN