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I just freshly installed win7 64 bit. Before I installed the graphics driver (amd 6310), the sleep option was greyed out. But after I installed, i could sleep. Why does this occur?

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Exactly how much detail, or what details are you looking for? –  BigHomie Feb 22 '13 at 13:27
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3 Answers 3

up vote 4 down vote accepted
+25

The driver you were using previously was likely reporting the device power capabilities for the device incorrectly. Device power states D0 and D3 are assumed to be supported by all devices, but for PnP devices, the driver must indicate if the device supports D1 and D2.

http://msdn.microsoft.com/en-us/library/windows/hardware/ff561058(v=vs.85).aspx http://msdn.microsoft.com/en-us/library/windows/hardware/ff559825(v=vs.85).aspx http://msdn.microsoft.com/en-us/library/windows/hardware/ff543162(v=vs.85).aspx

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Without a driver for the video card, how would the system know how to put it to sleep or, more importantly, return it to a sane state after waking it up?

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Apparently the old graphics driver was blocking the entering into the sleep state.

Whatever happens exactly when entering into sleep is actually determined by the manufacturer of your computer, so sleep problems may vary between different computer models. It may be that the default driver was handling badly your graphics card and was incapable of turning it off, and by reporting this to Windows was preventing sleep.

For analyzing sleep problems, one can use the powercfg utility.
If you are still curious about the problem, you can revert to the old graphics driver and run powercfg -energy to maybe find out some more information about this problem (then reinstall the new driver).

Many articles exist for sleep problems. See for example :
Evaluate the efficiency of Windows 7 Power Plan settings.

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Would the old graphics driver be the generic windows one? I did not have one installed previously as it was a fresh install of windows. –  agz Feb 19 '13 at 3:14
    
Windows uses the driver it sees as the best-fitted, using the generic driver if the adapter is unknown. Even if Windows recognized the adapter or its family, the Windows driver usually lags far behind the manufacturer's version, sometimes even years behind. –  harrymc Feb 19 '13 at 6:43
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protected by Breakthrough Mar 6 '13 at 13:08

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