What is "Link State Power Management"?

In the Windows 7 Power Options, under "PCI Express", I can adjust "Link State Power Management". The options are:

• Off
• Moderate power savings
• Maximum power savings

What do these settings do? Is there any reason to enable it when my laptop is plugged in?

1 Answer

Link state power management: PCI Express needs a continuous stream of data from the PCI Express device to the computer to keep them in sync. If the link state power management setting is set to conserve power the PCI Express device will basically power down and stop the continuous stream of data but it will need to power back up and sync before you can use it again.

— MAXIMUM pcguides - Configuring Windows Vista’s Advanced Power Settings