Enable CPU Core Parking

By

Joachim Nässlander

Published: 08 October 2009 1:44 PM CESTPosted in: Hyper-V Server 2008 R2, Windows Server 2008, Windows Server 2008 Core, Windows Server 2008 R2, Windows Server 2008 R2 CoreTags:

After hunting this information all over the vast global internet I actually found it in a performance related word document from Microsoft. The enabling of CPU Core Parking is NOT done in a group policy like it says everywhere, so you can close that MMC right away.

Instead fire up CMD and enter the following:
powercfg -setacvalueindex scheme_current sub_processor bc5038f7-23e0-4960-96da-33abaf5935ec 25

This line will allow the CPU to park 75% of it’s cores. As in if you’ve got 4 cores, 3 can park. If you’ve got a dualcore the number to park one core would actually be 50 then. Clear on that? (Don’t ask me about the long sub_processor number thingie cause I have no idea) (UPDATE: Now I do know, check http://www.nullsession.com/2009/11/24/powercfg-unleashed/ for more info on that string)

powercfg -setactive scheme_current

This will activate the settings you just entered, in the currently active powerplan.

Did it work? Check out Resource Monitor for an answer. The more cores you have, the more likely anyone will be parked one could say.

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About the Author

I have 10+ years experience of the IT-industry. The last years I've been heavily involved in Microsofts Technology Adoption Programs for Windows Vista, "Longhorn", Hyper-V, "Stirling", SCVMM and Windows Server 2008 R2. I'm was awarded an MVP in File Systems & Storage 2008, MVP in Cluster 2009, member of Microsoft Extended Experts Team and have been speaking at numerous events such as TechEd and TechDays.

3 Comments

1. Jaime Bula

   Posted May 30, 2010 at 3:59 AM

   Disabling CPU Parking is the best thing I’ve done for my i7 computer. It really improves performance. (i7 920, 6 Gigs DDR3, ATI 5770, Desktop Computer running Win 7 x64).

   I like to share my experience

   I tried 3 applications:

   DIRT 2: Now I can max out all Graphics at 1080p, and gained an extra 20 FPS!!. Frame rate became far more stable (sudden frame rates drops dissapeared),

   Heaven Benchmark 2.1: Now I can run decent tessellation ( Catalyst 10.5 also helped ) and got an average of 10fps more out of it.

   Visual Studio 2010: It might be only my impression but builds are faster (140.000+ lines of source code), XAML rendering and Intellisense work smoother.

   Overall disabling this feature on Desktop computers is a Must!!
2. Mårten

   Posted November 24, 2009 at 9:53 AM

   Hi Joachim,
   “bc5038f7-23e0-4960-96da-33abaf5935ec 25″ What string is this? Is this string for ALL servers or AMD or INTEL?

   and if i activate this do i need to type the same string to deactivate it?
3. Magnus Björk

   Posted October 9, 2009 at 2:36 PM

   Great info but you have way to many cores my friend, I have great use for a couple of them…