Can't give a precise number at this moment, i'm using an UPS eaton Ellipse 1200 (1200 VA) via network, the ups is connected via usb on my DS918+ but there are three devices idling on the same UPS my server, a Synology DS918+, and a Synology DX513 (with 5 Seagate exos x16 16TB), i can give you a recent pic all hard drives off (files are served y cache) and just 2 transcoding on plex, plus the two Synology idling on the same ups :