Microsoft has made available for download an update designed to boost power-saving capabilities for the latest Windows client and server releases. Microsoft noted that the update could allow for potential power saving, provided that the machines running a 64-bit (x64-based) version of Windows Vista SP2, of Windows Server 2008 SP2, of Windows 7, or of Windows Server 2008 R2, were equipped with an AMD multicore CPU. According to the Redmond company, the refresh can tweak the Windows operating systems mentioned above in order to leverage the Enhanced C1 state (C1E) for lower power consumption, which is a feature of AMD multicore processors.

“The local Advanced Programmable Interrupt Controller (APIC) timer is programmed to count even when it is not being used. Therefore, the local APIC timer runs in the C1 sleep state continuously at a constant rate regardless of performance state (P-state) transitions. This behavior causes the computer to consume unnecessary power. However, AMD processors support an inactive state for when the CPU APIC timer is not being used. Therefore, an AMD processor can enter the low-power C1E state. This low-power state saves up to an additional 10 percent in power,” Microsoft stated.

In addition to running just the 64-bit flavor of Windows 7, Windows Server 2008 R2, Windows Server 2008 SP2 and Vista SP2, end users will also need their AMD multicore processor to actually support the C1E state. The update only works in conjunction with supported Windows clients and servers as well as with C1E-capable AMD multicore processors in order to deliver power savings via the sleep state.

And although Microsoft is saying update, fact is that the downloadable bits are not a fully fledged refresh, but actually a hotfix. “This hotfix is intended to correct only the problem that is described [here]. Apply this hotfix only to systems that are experiencing the problem described [here]. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix,” Microsoft added.