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Does HDD in Sleep mode under Windows 8 still spins - as it's saves your RAM into HDD? I'm concerned about hdd when carrying laptop around in a bag when it's in sleep mode. Or it is Hibernate which turns off my hdd - as it's saves all into RAM?

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migrated from Nov 12 '12 at 4:21

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It depends if your laptop motherboard supports some configurations. According to this blog post and msdn , there are 3 idle states that you can use on Windows:

S1 - CPU Stopped: The power consumption is reduced by a fraction (Five Watts to Thirty Watts of Power). This state is used in computers without S3.

S3 - Sleep (Suspend to RAM): the PC is in a standby state and all the devices (hdd, fans, optical drive) are powered down.

S4 - Hibernate: everything on the RAM (data) is saved on HDD. It still drains some battery, but even less than S3.

You can find brief explanations about the sleep, hibernate and (new) hybrid sleep states at Microsoft here.

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That is incorrect. Windows 8, while in S3 (sleep), spins down the hard drive. The difference between sleep and hibernate, essentially, is that hibernation removes power to RAM, and so resume will have to read saved state from the hard drive. – Michael Petrotta Nov 12 '12 at 2:33
"spins down" ? What do you mean. – Primosz Nov 12 '12 at 2:36
@Primosz: "spins down" means "turns off" (no longer spinning). – Michael Petrotta Nov 12 '12 at 2:39
Source: the Windows 8 machine I'm sitting in front of right now. And the fact that this is what Windows has done in every version that has supported sleep and hibernation. But let me see what I can find. – Michael Petrotta Nov 12 '12 at 2:47
Best I can find, @Primosz:…. And again - I've personally verified this, basically every day, on every PC and on every version of Windows I've used for the past ten years. – Michael Petrotta Nov 12 '12 at 2:53

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