After I shutdown my laptop completely and when I reopen the lid its turns on automatically so, I believe the laptop is not shutting down completely because otherwise how does laptop knows I opened the lid. HP pro-book 450 g3, windows 10.
12 Answers
See Solved: How does computer know when lid is closed? - Dell Community
There's a lid switch. A mechanical switch. On older laptops, you can often see a small stick button sticking out of the surface, on most modern laptops it's somewhere in the hinge. The button then "sends" an ACPI signal to your operating system of choice. (Very simplified description)
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The answer is that somewhere in the system there's a switch that opens and closes when the screen is open or closed. On older systems the switch was visible, usually on the strip above the keyboard. On newer ones, it's very often a magnet hidden in the frame of the LCD panel that activates a switch built into the mainboard when you close the cover.
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Actually it knows because when you close the lid because there is a little guy with binoculars who's job it is is to monitor whether the computer is opened or closed. When the lid is closed he calls from his lookout position to the little guys down below, whos job it is is to run to the power switch and click it so the computer shuts off or goes to sleep.
See also What is the exact mechanism by which the laptop knows whether you closed it's lid or not?
That is because you didn't shut down your laptop completely. The laptop is in sleep mode. It means that the laptop is using low power to continue running the open programs you have to select shut down to close your laptop properly. If you leave the laptop in sleep mode for, like, 15 to 20 days your laptop wil take longer to boot the next time.
