I know it varies based on models, but is there an average? The numbers i’m finding on Google are weird, some say 120 watts, some say 1000 watts, some say 400.
What about a 20 GB, with a 1.2 Ghz processor, 256k of ram, a 15" color monitor & a low model lexmark printer?
I’d say around 200W peak on about the fastest system available today. During typical usage, less than 50W. On your system, I’d say it’s likely to max at around 100W. Add another 50W or so for the monitor, and the printer should consume almost no power when idle, if it’s an injet.
I put your specifications into the APC UPS selector at www.apc.com. It suggested a 725VA/450W UPS operating at 26% capacity, which suggests your system draws somewhere around 190VA or 120W. APC’s UPS selector is pretty good, in my experience.