Depending on your video card, some sleep states may not be available on your computer. You can see what states are available as well as what states are unavailable and why. This is done by using the command-line utility, powercfg. Here’s how:
1. Click the Start.
2. Click All Programs and select Accessories.
3. Select Command Prompt.
4. At the command-line, input powercfg -a and press the Enter key on your keyboard.
The states are represented as follows:
S1 – Stand By (Power On Suspend) – no system context is lost
S2 – Stand By – CPU and system cache context is lost
S3 – Stand By (Suspend to Ram) – system memory context is maintained, all other system context is lost
S4 – Hibernate – Platform context is maintained.
As you can tell, S1, S2, and S3 are all various aspects of the Sleep function. If you are running an incompatible video card, some or all of these states will be unavailable.