On all of these UPS's, the inverter is going to make some type of noise. The better ones that are able to put out more than about 400 Watts will have a fan. Some allow you to disable the alarm. If not, you can wire a switch in series with the alarm that is inside, if it is easily accessible, but this will void the warranty.
What we do in the sound and production studios, is that we locate the UPS's in another room with the computers. The computers all have fans in them, and are also noisy. We have the monitors, keyboards, and mouse's extended with Cybex boxes, or the equivalent. If you want the computers in the same room, you can always have the UPS's in another room, and run AC extensions through the walls.