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 Post subject: Re: Is it safe to do this...?
PostPosted: Sun Jan 02, 2011 9:18 am 
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Joined: Fri Jun 13, 2008 3:21 pm
Posts: 1700
Location: Cambridge, United Kingdom
DavidCooper wrote:
A sleep mode on the other hand is just an extremely low power state - the system is not actually off at all. Removing power during sleep will cause you to lose data, and you can't boot off a different disk when returning from a sleep mode.

Sleep mode on the other hand isn't going to lead to a reboot of any kind, so you're always going to continue from where you left off with whichever OS is active. The battery's still going to run down fairly fast, but it's useful for stopping work from time to time to have short conversations with people. I don't know how easy it would be to do this from my own OS as it may have to do something via ACPI to get into sleep mode unless sleep mode has already been tied to the power button instead of hibernation, and even then I don't know if either system will work just through pressing the power button alone. I'll have to try it to find out
(and hopefully I'll be ready to do that in a few days).

Sleep mode is most accurately called "suspend to RAM" - and on a good machine, most of the components (including the CPU) will be powered off or in a low power state. You can get laptops now (e.g. the new MacBook Air) which will last a month in sleep. Even my full notebook (a current gen MacBook) will last multiple days in sleep.

As for battery life: Mine claims 10 hours of web surfing (and achieves this in practice!), but of course this drops to ~2-3 hours under heavy CPU load, and ~1.5 hours under heavy 3D. You won't get anywhere near full battery life in your OS - the measurements are taken with the CPU unloaded (and therefore PowerNow!/SpeedStep has underclocked it, and it spending significant time in halt/deeper sleep states). To access such power saving features... you need ACPI ;)

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