The PCI Express option Link State Power Management is part of the PCI-E Specification and works in conjunction with the active-state power management (ASPM) in Windows 7.
It's a complex subject but can be simply described as the following.
There are basically 2 levels of power management in the PCI Express options.
The difference between these 2 options are the power savings versus the Latency (Time to recover from the Sleep state).
If you select the first option Moderate Power Savings, the power savings are less, but the time to recover from the Sleep state (latency) is much shorter.
If you select the Maximum Power Savings, the power savings are greater, but the...