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Is it only the RAM, a RAM controller, and perhaps a BUS controller related to RAM controller and a Power system? I assume the CPU is dead, because that might require cooling. And I don't see any cooling during sleep. Then again, if a memory system or more are on, that might had required cooling.

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It depends on the sleep state.

According to Wikipedia's ACPI Article:

  • S1: All processor caches are flushed, and the CPU(s) stop executing instructions. Power to the CPU(s) and RAM is maintained; devices that do not indicate they must remain on may be powered down.
  • S2: CPU powered off. Dirty cache is flushed to RAM.
  • S3: Commonly referred to as Standby, Sleep, or Suspend to RAM. RAM remains powered
  • S4: Hibernation or Suspend to Disk. All content of main memory is saved to non-volatile memory such as a hard drive, and is powered down.

Very, very few RAM subsystems have ever required any kind of active cooling. Even of those that did, most only required it when under load. Simply maintaining state wasn't enough to require that. Beyond that, only the RAM itself needs to maintain state in S3 -- the RAM controller is only required as an interface between the system and RAM, and can be safely powered down since the rest of the system is as well.

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Which one is sleep of windows 7? –  leladax May 8 '12 at 13:45
    
It depends on the system. Many of the Dell Optiplexes I have on site allow me to switch the default sleep setting in the BIOS between S1 and S3. Most reasonably modern systems will sleep to S3, but buggy drivers could force Windows to use a lighter state. –  afrazier May 8 '12 at 16:04
    
I wonder if RAM supporting systems in the chipset or CPU have to be on. –  leladax May 17 '12 at 18:54
    
It shouldn't -- RAM refresh clock shouldn't be driven by the memory controller. –  afrazier May 18 '12 at 14:20

Yes, in sleep mode only ram uses power, otherwise you cannot restore the state when it wakes up. All other parts do not consume power, at least in theory. The power usage should be minimal and cooling should not be required as CPU generates most of the heat, nor ram.

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