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I heard that OS X Mountain Lion on a Mac has a feature called Power Nap :

With Power Nap, your Mac sleeps but your applications stay up to date. So you have the latest information — such as mail, notes, reminders, and messages — when your Mac wakes up. Power Nap performs Time Machine backups to Time Capsule and downloads OS X software updates while your Mac sleeps, so you can begin installing as soon as you wake it up.

Can Windows do the same on a PC?

Does Windows 8 / Windows RT have any new features that can do any special task while it is sleeping?

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Certainly, by a suitable redefinition of the word "sleep", as Apple seems to have done. –  kreemoweet Sep 3 '12 at 17:49
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4 Answers 4

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Windows (Vista+ anyway) provides something similar, and can/will wake your computer from sleep states to do updates, backups (etc).

Having said that, your motherboard's firmware needs to support, and be setup to use, this feature.

They're referred to as 'Wake Timers' in the Power options (where you can enable and disable them).

The system is part of the Task Scheduler (primarily). You can find it by opening a task in Task Manager and looking under 'the Conditions' tab, where you will find a "Wake the computer to run this task" check box.

There you can also make you own tasks that will wake up the system to do what you'd like.

More info here (SuperUser) and here (MS).

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Good answer, but note that this feature is not nearly as sophisticated as Power Nap. Macs with Power Nap wake up and go back to sleep for brief periods on a regular basis, without turning on the monitor or even the LEDs. This happens more often if the laptop is on AC, and stops happening if the battery is 2/3 depleted. –  Isaac Rabinovitch Sep 4 '12 at 18:52
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The "sophistication" of Windows scheduled tasks lies entirely with the task code itself, and is potentially unlimited. There is no necessity to turn the monitor or anything else on, and they can create new scheduled tasks as necessary. –  kreemoweet Oct 31 '12 at 5:29
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Sleep is a lowered power state, but it is not turned off. Obviously, if the computer was off, nothing would work.

Windows, as far as I know, doesnt provide programmers the ability to write code that executes while the PC is a sleep state.

However, that does not mean programs are not running. Windows needs to detect events that wake the PC. Events can be ACPI power button press, mouse movements or clicks, magic packets (Wake on Lan), or keyboard presses. I might be missing some. Windows is also "awake" enough to properly shutdown a sleeping laptop if the battery is about to die.

Now Apple allowing certain functions to be done while sleeping is a double edged sword. Yes, backups and such can occur, but if the device was on battery power it would drain faster, defeating the purpose of sleep's low powered state.

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Sleep state does mean that programs aren't running. The OS doesn't detect events when it's sleeping. Events are external things that cause the OS to wake up. –  Isaac Rabinovitch Sep 4 '12 at 0:59
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the OS absolutely detects events while sleeping, otherwise it would never know to come out of sleep. –  Keltari Sep 4 '12 at 1:51
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@Keltari: The OS is woken by the BIOS. Therefore, the BIOS detects the events. –  MSalters Sep 4 '12 at 9:13
    
Sorry to be such a nitpicker, but neither the OS or the BIOS has the ability to run when the sytsem clock is turned off, as it is in all sleep states. No system clock, no synchronization, no synchronization, no code getting executed. The hardware simply has the ability to respond to external events by bring up components that have been powered down and telling the processor to execute restart code. It's not all that different from what happens when you power up from scratch -- it's just a little more sophisticated. –  Isaac Rabinovitch Sep 4 '12 at 19:14
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Windows actually has multiple sleep states. Each sleep state conserves power and allows the system to resume working quickly, but the hardware is pretty much inactive. No software can run when a PC is asleep.

Not being a Mac person, I hadn't heard of Power Nap before now. According to this knowledge base article it's actually a way for the Mac to power up briefly to perform routine tasks. The lights don't go on, but the system is active and consuming power. Strictly speaking, the Mac is not asleep when Power Nap tasks are running.

It's one of those cool features that Apple loves to invent. Requires special hardware support, so you can't do it on a PC. Wouldn't surprise me if it appeared on PCs eventually.

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It doesn't require special hardware support, unless you mean keeping the power lights off. Windows or Linux could do it by only waking the CPU and RAM, then running a special process instead of resuming the complete system where it left off. Hard drives and displays can already sleep independently of the CPU, so just leave them turned off. –  Zan Lynx Sep 3 '12 at 23:54
    
Only Macbook Air and Pro manufactured since mid 2011 support Power Nap. This tells me that hardware support is needed. –  Isaac Rabinovitch Sep 4 '12 at 1:11
    
Not really. The requirements are for a SSD drive, which helps reduce the amount of power used. But that's not special hardware, those laptops came with SSDs. –  Benjamin Schollnick Sep 4 '12 at 19:08
    
These models come come with an SSD drive or a regular drive. Power Nap requires both an SSD drive and an Air or Pro manufactured since the middle of 2011. –  Isaac Rabinovitch Sep 5 '12 at 5:27
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Betting the Mac is not actually asleep during this time, but running the CPU in the lowest speed setting and keeping the display off. If it was really slick it might not even spin up the hard drive and cache filesystem writes until next actual power up, but I don't know how they actually do it.

Windows introduced a feature called "Sideshow" that would update a "Sideshow" display with information periodically. I believe it was envisioned to update media-style remote control displays with RSS feeds and possibly small attached displays on laptops themselves. It would wake the PC up from sleep to do this, but I'm not sure if the computer would look like it was awake during this time (knowing PC OEMs and their implementations of ACPI, probably so).

So I believe there's some functions buried in the vast Win32 API or .NET or Presentation Foundation or whatever that could do something similar, if an application developer wanted to.

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PowerNap will not cause your system to make a peep, it is only compatible with systems that have flash memory. It also is advertised to never spin up a fan. –  Chris Wagner Sep 3 '12 at 23:42
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You shouldn't bet on an answer. You should do a little googling and find out for sure. –  Isaac Rabinovitch Sep 4 '12 at 0:54
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