People are right, it makes this funny high pitched sound in a rhythmic pattern

The UPSs that my past employers have purchased for the office computers produced a very loud buzzing sound under transient load conditions

Sound from this thing is annoying high pitch sound no matter the load....however Amazon

To test the system, I disconnected the power, and the battery lasted for over 2 hours of use with the TV on vivid display and the sound at a fun level for watching movies with a friend

Also of note, the unit does make a rather loud buzzing sound when it fails over to battery.

If they could fix these two annoying sounds then this would be a five star unit

If it thinks the battery pack is bad, it starts alarming EVEN IF YOU HAVE DISABLED ALARMING IN THE POWERCHUTE SOFTWARE!!!!!The alarm sounds for 60 seconds, and pressing the "silence alarm" button on the front panel of the unit DOES NOT SILENCE THE ALARM FOR MORE THAN 5 SECONDS!Even worse, it repeats the

Now it makes a loud sound.

The BR1500MS does make a very faint sound during load transits (i.e. caused by computer power up and power down)

If you wake the display on the APC it makes an even more annoying buzzing sound.

The battery drained, the unit On/Off switch was unresponsive and began making a strange sound .

Thankfully, the annoying beeping sound can be muted on the front panel

The sound from a defective unit is an annoying low-pitch high-frequency/sonic sound that almost sounds like a small insect or tiny mouse, and the sound goes off every 4 or 5 seconds like clockwork

When the iMac is on the backup battery from the new UPS, there is an odd fairly loud sound from the center bottom of the iMac.

The unit also makes a whiny/buzzing sound whenever the screen is on, but that goes away when the screen turns off.

Power outage at the house (Storm), lost connectivity (router, etc.)...the "U" in UPS is false with this thing