Why does my computer keep turning on?

My desktop PC running Windows 7 with Gigabyte motherboard keeps turning on spontaneously. I put it on sleep, then come back a few hours later, and it's on. I have verified that no one else used it. My keyboard and mouse are able to wake the computer if they're used, but no one is using them, and they haven't caused this problem in the past. I've had the computer for a couple of years now; this problem has just recently started.

 

Can moving the mouse wake it up? If yes then it's probably vibrations from the floor moving the mouse hence waking it up.

 

Yes, moving the mouse can wake it up. You mentioned the floor, and that reminds me that we recently replaced the carpet in the computer room with tile. Hmmm....I wonder.

 

That would be it cause the carpet was absorbing vibrations

 

Control Panel - Hardware and Sound - power options - change plan settings - change advanced power settings - sleep - Allow wake timers - Disable.

 

I had the same thing. Changed it so the mouse can't wake it up, fixed it.

 

I did this and will see what happens now.

 

Disabling wake timers worked, thanks.