How long will the UPS last?

Question

Uninterruptable power source

There is an uninterruptible power supply, PowerWalker VI 850 SE USB, and a 25Ah battery is connected to it (two for 9, and one for 7), and a powerful cooler for cooling (size 80, 3400 rpm), so the i7 4790K server will be connected to it (possibly overclocked to 4.7GHz), SSD, and 32GB of RAM. Who knows how long he can last? Perhaps there is some formula?

Answer 1

Any formula will require power input. Here it also result in a question.

Answer 2

If all batteries are 12V, then their power is approximately 300 W * h.
Let's take the efficiency of your UPS as 85%.
Then it will hold a load of 300 W for about 50 minutes.
Everything is very approximate and does not take into account the reactive component, battery wear, the fact that you have assembled three different batteries into one, and so on.