APC RS BR800i any explanation and presumed problem

[Anonymous user]

Hello all, here Laura from Italy.
I have a new APC RS BR800i. Now i have 2 questions about this UPS:

1) When i turn on the unit, first led green flashes, and is it ok...but immediately after any seconds (9 seonds?), yellow LED ("on battery" led) lights on, the unit emits a buzzing for a few seconds (10 seconds), after this seconds the yellow led switch off and everything works normally with only first green led on. But is this normal behavior? Why when i swith off the unit and, after, i power on it the yellow led lights on and a buzzing appears for 10 seconds?

2) When i work on my pc the unit is very quiet. However, when consumption of the PC (in game) increases, the unit starts to emit a low non continuous buzzing. It's not annoyingIt's but is it normal?

ps.: my power supply is an active PFC by Seasonic.