Everybody pays the power bill. 
Well… except maybe the power company.  But who wouldn’t want to reduce that bill?  Not to mention their environmental impact?
The biggest power savings many organizations will probably experience with Windows Server 2008 R2 is through server consolidation with Hyper-V, the built-in Hypervisor.  But we also had several other goals in mind to help people manage power and control costs while we were developing R2.
One of our goals was to improve power efficiency, out-of-the-box, with no manual configuration required on the part of administrators.  This improvement is derived from a variety of features, including an improved processor power management engine, timer coalescing, tick skipping, and R2’s new core parking capabilities.
As you may have already heard, these out-of-the-box improvements can help improve power efficiency by up to 18% over Windows Server 2003 running on the same hardware.
Some have asked, “Will every one of my servers save 18 percent?”  In brief, no.  To be clear, just as a car’s gas mileage depends on many factors – make and model, average speed, city or highway driving, today’s traffic congestion, and how well maintained it is – improvements in power efficiency will vary, as well.  Your specific savings will depend on many factors – on your particular server, your specific hardware configuration, the type of workload that server is running, and the server’s utilization level from moment to moment.  The only way to nail down specific savings is to actually test it.
While working on these power management features during the development of R2 we tested a variety of servers – new and old, large and small, relatively busy and relatively idle, running various workloads – in order to ensure that the changes we were making would help improve power efficiency across a wide variety of environments.  And they do.  But the specific improvement you see will depend on your own particular environment.
Another goal for R2 was to provide new capabilities to help people measure and manage power consumption.  If you walk up to a server running Windows Server 2003 or 2008 and fire up perfmon, for example, you can’t see power consumption, let alone easily collect that data across your environment.
But with Windows Server 2008 R2 and supporting hardware – such as the recent G6 servers from HP which have earned the Enhanced Power Management Additional Qualifier (www.windowsservercatalog.com) – you can monitor power consumption locally or remotely via WMI, change power plan settings, and even do power budgeting.  Of course, these features do require some work on the part of IT administrators to make use of this data – to set goals, make changes, and measure impacts. 
R2 offers the possibility to impact the environment – and costs – in a worthwhile way for organizations large or small.
Dan Reger
Senior Product Manager, Windows Server