Windows 7 wakes from sleep
When you put Windows to sleep, you expect it to stay asleep, but various devices can cause it to wake. To see what might be waking your Windows 7 rig from its slumber prematurely, do a Windows search for “cmd” and, in the command line interface that appears, type the following.
This should show you the last hardware device which caused your PC to wake. However, in our experience this command is not 100% reliable. If nothing shows up, try the following.
powercfg –devicequery wake_armed
This tells you every device that has permission to wake your computer.
Now open Device Manager and seek out the devices matching what the command line reported. Once found, double click to open Properties, and then head to the Power Management tab. Here, you’ll find an “Allow this device to wake the computer” checkbox. Un-check it.
If you still have problems, then the issue might be software related, not hardware centric. Windows search for Power Options, and in that window open the power plan your PC uses. Now click the “Change advanced power settings” button.
Scroll down until you find the Sleep tree. Expand it, expand “Allow Wake Timers,” and disable it. Software will no longer be able to wake your PC.