Question about APC Back-UPS AVR, IEC

The question is: How much power does the PC currently draw, i.e. during operation? If the power is higher than 300W, the UPS will not function according to its specification (among other things, the autonomy time is correspondingly shorter). At max. 850W the UPS would be almost 3x overloaded = not good, possibly it kills the UPS, in the best case only the fine-wire fuse (if present).
However, with a wattmeter (search for "energy meter" - 12604028) it is very easy to measure the power when the PC is in full operation.
Another consideration is how long the UPS should "last". If it is only a matter of shutting down the PC cleanly in the event of a power failure, the UPS can be dimensioned just above the effective power consumption. The UPS above lasts about 1 minute at full load. Here I would consider a UPS with at least 1500VA/900W.

This UPS has not given me any problems yet. Reliable, inexpensive.
I use the device for devices that require few watts (routers, switches, POE switches, NAS). It has never failed since I got it.