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Thread: H81M C7 state option is missing from uefi




  1. #1
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    Default H81M C7 state option is missing from uefi

    Hi,

    I bought Asrock H81M mobo and I would like to know how to enable haswell c7 state in uefi/bios. Page 63 in the manual shows "CPU C7 State Support" option but I can't find it in my bios (C1E, C3, C6 and Package C State are there and set to auto). I have Haswell ready psu, Pentium G3420 CPU and MSI hd7790 GPU.

    Please help, maybe I should enable deep sleep option or something first? Does desktop pentium cpu even support C7 state?

    BTW Is there any way to disable power on usb ports after shutdown on this mobo?

  2. #2
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    Default Re: H81M C7 state option is missing from uefi

    You're asking the right questions, and although I could not find specific information about your Pentium G3420, I did find this in an Intel Haswell document:

    C7 state may not be available on all SKUs.

    SKUs are the Intel codes to identify different processors, so the statement could have been written, "C7 state may not be available on all Haswell processors".

    So the C7 option is not appearing in your board's UEFI because the G3420 probably does not support it.

    I also found this in the same Intel document:

    Package C6 state is the deepest C-State supported on discrete graphics systems with PCI Express Graphics (PEG).

    Which means if you use a video card in the PC, the C7 state will not be available.

    In your case, I think C7 is just not supported by your Pentium processor.

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    Default Re: H81M C7 state option is missing from uefi

    Thanks, I found this document too ("Desktop 4th Generation Intel® Core™ Processor Family and Desktop Intel® Pentium® Processor Family Datasheet – Volume 1 of 2"), but I thought that SKU might be a h81 chipset and asrock manual was just wrong (universal for h81m, b85m, h87m etc.). Is there any intel's H81 chipset datasheet?

    I don't know how I didn't see this statement "Package C6 state is the deepest C-State supported on discrete graphics systems with PCI Express Graphics"
    I will try without VGA card and with monitor connected to iGPU.

    I thought all Haswell cpus support new C6/C7 states, pentium should be good for HTPC with even lower power consumption...

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    Default Re: H81M C7 state option is missing from uefi

    I have a link to the Intel 8 series chipset datasheet, but it doesn't list the H81. Here it is anyway:

    http://www.intel.com/content/dam/www...-datasheet.pdf

    If you check the following document, checking pages 57 and 58, you'll find a discussion of C-States. It explains how for some processors, the C6 state will actually be better for power savings than the C7 state, and that not all processors have the C7 state. The document won't allow you to even copy text from it, at least with my version of Adobe reader, so I can't put that text in this post:

    http://www.intel.com/content/dam/www...-datasheet.pdf

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    Default Re: H81M C7 state option is missing from uefi

    I asked about Pentium on Intel community site and their support guy said that only Haswell Core cpus from i3 to i7 support C7 state.

    I tried without dedicated graphisc card and the lowest possible state for pentium is C6. I checked it with Techpowerup's Throttle Stop software.

    Thank You for your help.
    Last edited by endriu; 12-03-2013 at 06:51 AM.

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