Saving power is important, especially on mobile devices and laptops. Every CPU has a built-in feature to shut down different parts of a computer to reduce power needs. It’s up to the techs to make sure the power management settings are optimal for the users.
- So pretty much everything else can be handled in Windows, but first, before we get into Windows, I want to make sure we understand that ACPI has power states. And they're numbered S0 through S5. Now, a lot of times when you go into BIOS, you'll see things like wake on LAN at S5 or something like that. I want to make sure you understand what these S levels are, 'cause you don't even have to know them all. First of all, either ACPI is enabled or it's not enabled. On most systems today it's just enabled when you power up the computer. You can't even turn off ACPI anymore. So ACPI S level 0 basically means ACPI is on, but nobody's using it. We haven't got anything turning off, or whatever might be happening. The next level is going to be what we call ACPI level 3. ACPI level 3 is what we call a sleep mode. Now, when your computer goes into a sleep mode, your CPU stops working, but your RAM keeps running. So whatever is in RAM at any given moment, it kind of like freezes it right there, and it's going to be sitting there and RAM's going to be continued to be powered and keeping it there until you're ready to come back to your system. So a sleep mode is pretty easy to come back from. When we get to ACPI level 4, what we're talking about there, is hibernation. Now, hibernation means everything that's on RAM is copied to a file on your hard drive, and then even RAM is shut off. So hibernation uses a lot less power than sleep, however, it takes a lot longer to come out of hibernation mode. You can actually see the file, where all your hibernation settings are stored, on a Windows system that's in the root directory of the C drive. Let me show it you. So I've already popped up a command shell and what I'm going to do is I'm going to type dir /ah, show me all the files with the hidden attribute. And if you take a look right here, do you see hiberfil.sys? That is actually where your RAM is copied to when your computer goes into hibernate mode. When would you choose sleep versus hibernate? Well, it's completely up to you. The only benefit is that hibernate uses less power than sleep but it takes a little bit longer to come out of. So keep that in mind when we make some choices here. Okay, let's come back into Windows now and this time what I want to do is actually configure our power. Now you can do this through settings but I'm a little bit old school so I still do it through control panel. And we're looking for power options right here. What Windows likes to do is it creates what is called a power plan. It's going to make two power plans for you, balanced and high performance. Balanced is basically, if I'm at ACPI level 0, and I am running full speed, I can still turn off a monitor without going into sleep mode. I can still turn off a hard drive without going into sleep mode. Get the idea? So even at ACPI S0, I can say turn off the monitor after three minutes. And I'm still wide awake, just hit the keyboard, boom, I'm right back. However, it does cut down on a lot of power. Your system by itself, the CPU and RAM, compared to your monitor and a bunch of spinning hard drives, doesn't use that much power. If you want to save power on a laptop, turn off the monitor, turn of the hard drives, and you're going to be doing really, really well in terms of power save. If I want to I can have some other choices. For example, choose what the power buttons do. And this is that soft power. If I want to, I can say when I press the power button on my laptop when I'm on battery, I can go into sleep mode or I can completely shut down the computer if I want. This is where I make those choices. When I close the lid, when I am plugged in I go into sleep mode but maybe when I close the lid I want to go into hibernate mode. So this is where I can make those types of choices. I'm going to save this. I like these choices. Choose what closing the lid, that's pretty much going to bring us back to the same spot. If I want to, I can actually create a power plan. Now a power plan, they give you three choices here, you can make your own custom plan. We're going to look at the balanced plan though. So it's going to give me settings for my display and actually for just putting my machine to sleep. That's not hibernate mode. Now if I want to, I can change the plan settings and I can go into advanced power settings and now I can be extremely detailed about how I want things to work. For example, what do I want my wireless adapter to do. So I want to set it for, they actually have a medium power setting. We can actually go in there and detail that if we want to. Even things like my PCI Express slots. All kinds of stuff. I can configure this at a very, very detailed level. The bottom line is that the biggest problem most people have with power management on a laptop is that laptops magically do things and they don't know why. I'm sitting here working away and all of a sudden my computer turns off. Well, folks, you need to take some time and go into your power management plans and configure them to work the way you need them to. And also remember, closing a lid or pressing a button is extremely programmable. If you don't like what your buttons and your lids are doing, change them. (bluesy music)
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