Dell XPS Speed Shift

Discussion in 'Dell XPS and Studio XPS' started by pressing, Oct 8, 2016.

  1. arshcaria

    arshcaria Notebook Enthusiast

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    Thanks for the guide. Can I restore it to default (disable speedshift) by typing setup_var 0xD8 0x0? In other words, is it reversible?
     
  2. goodwin_c

    goodwin_c Notebook Enthusiast

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    yes, you can set 0x0 to disable Speed Shift. It is fully working option, just Dell doesn't care about us to add it into bios interface. And they are assholes, because Speed Shift has zero requirements to bios or motherboard or machine vendor. It doesn't need any special implementation in UEFI code. It is fully hardware solution inside of CPU package. So it needs only one small marker from bios for windows to tell that it is supported in case if CPU supports it (and skylake cpu's supports it)
     
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  3. pressing

    pressing Notebook Deity

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    Thanks Goodwin,

    Enabling SpeedShift in BIOS should permit one to adjust (the fantastic) EPP for max performance or max energy savings in the Windows "power options" via a simple dropdown box:

    Control panel>hardware and sound>power options>[select a plan]>change plan settings>change advanced power settings>processor power management>processor energy performance preference policy.

    If the "processor energy performance preference policy" is not viewable, go to the first page of this thread to enable (there are a few other dropdowns you can enable also). That is a dummy variable on my system (changing from 0% to 100% does nothing). But with your BIOS tweak, it might enable the dropdown. There is a huge difference in responsiveness between 0% and 100% so will be obvious in 2 seconds of internet surfing.

    If you can't adjust EPP, from the Intel documentation, it seems OEMs would set EPP somewhere in the middle of the range. Regardless, you can always use ThrottleStop to enable SpeedShift and adjust EPP (note the EPP scale goes from 0-255 rather than 0%-100%).

    FYI - I currently use ThrottleStop which requires that SpeedStep MUST BE enabled in BIOS. Since SpeedStep is laggy, I disable it via ThrottleStop (just uncheck the box). You can confirm that SpeedStep is disabled and SpeedShift is enabled via the free HWiNFO64 software (summary tab EIST=red and SST=green)
     
  4. Rockstar75

    Rockstar75 Notebook Geek

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    Thanks from me, too!
    I just tested and it works without a problem. At first I had to disable UEFI secure boot. Despite an error regarding the size of the variable (it returns 0x00 instead of 0x0) everything is ok. The value I entered was 0x1 (which was reported back as 0x01). HW64 is green!

    Thanks for your effort! So its kind of funny that Dell will refund my machine for the missing SpeedShift and now it works.
     
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  5. Rockstar75

    Rockstar75 Notebook Geek

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    pressing, I tested the power-plan options you mentioned and it seems to work. If setting it to "100" and observing the multiplier with HW64, the CPU is stuck at around 800Mhz. Setting it to "0" the multipliers stuck around 3,2GHz with one core in Turbo. So setting the EPP by dropdown menu works.

    (I edited this post, because I got pressing wrong).
     
    Last edited: Dec 2, 2016
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  6. blurblur

    blurblur Notebook Guru

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    I tried this, and it works, thanks!

    However, the BIOS update to 1.2.16 failed with the error "Error accessing BIOS monothonic protocol" when I tried to flash the latest BIOS. I set it back to 0x0, ran BIOS update again and it worked.
     
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  7. Techland

    Techland Notebook Consultant

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    Now that 1.2.16 is freshly out I tried it too. Got a bit confused due to the description being 'coarse', so to say. I used my Dell recovery USB stick, made from the original Dell Windows installation file, and replaced the efi file on it. Disabled Secure Boot in BIOS, and bootet straight into a command screen (EFI shell? I expected something different), with just saying 'grub'. No colors, nothing fancy. Typed in the commands, rebooted, and checked with hwinfo64 that SST is green.

    Now I got a bit confused - is EIST/SpeedStep supposed to be still active or not? I disabled it in BIOS, but then Turbo is also disabled (shown by hwinfo64 in red), capping the performance by at least 10%, easily to see as the cores no longer reach peak CPU frequency. I used the old CPU Rightmark benchmark to verify that. So I enabled it again in BIOS - full performance is back.

    I then added the new features to the advanced power plan settings. Yes, EPP indeed is controlled from there easily, and the changes can be observed in hwinfo64 in real-time. I have no clue what the time window setting is good for, and could not get it from trying values between 0 (default) and 10,000 µs.

    Deactivating SpeedShift (the autonomous mode) - I have no clue if that works or not. Simply because I also did not find a way to measure/demonstrate any differences on my system so far. And hwinfo64 still says SST green when disabling it via the dropdown menu.

    I wonder if the reason that Dell doesn't add SpeedShift is that Windows isn't ready for it. Seriously, Dell will not add a function that requires the user to add complicated command lines into an admin box to be able to control that feature. Those controls should automatically show up as soon as SST is detected.

    Also the not noticable performance advantages in real-world usage are disappointing. Why add something where users will later claim it doesn't work because they see no difference?

    I know that user pressing has an example where it improves performance. I can't reproduce the same with other music apps and interfaces. I got 32 samples over USB runing quite well, with some crackling at 100% CPU from an outside source. That did not change with SST, not at all.
     
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  8. arshcaria

    arshcaria Notebook Enthusiast

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    If you are using high performance power plan with AC plugged in, there should be no performance difference because cpu frequency is already fixed at highest. Speed shift is more for balanced and power saver plans.

    Also, if Dell supports speed shift natively in BIOS, you will not need to use any command line to enable it, right? You got wrong logic.


    Sent from my iPad using Tapatalk
     
  9. Techland

    Techland Notebook Consultant

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    Read again. Enabling SST in Bios (what we did) must bring up the advanced power plan options in Windows automatically. Which is not the case but instead requires the command lines typed in found on page one (post 10) of this thread.

    Also I tested with Balanced mode. Meanwhile I found other posts in other forums claiming the exact same thing. Got it working but not difference...
     
  10. arshcaria

    arshcaria Notebook Enthusiast

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    Sorry, I didn't know you meant showing EPP settings in power plan options.

    Yes, you will need these command to show these values.

    However, the three built-in power plans have their default EPP values, which means most users don't have to change it.

    upload_2016-12-3_13-36-15.png

    These values are hidden just like many other hidden ones are.



    EDIT

    The attached screenshot cannot show up. Below is the defaul EPP values for High Perf and Battery Saver power plans.

    High perf

    Code:
    Power Setting GUID: 36687f9e-e3a5-4dbf-b1dc-15eb381c6863 (Processor energy performance preference policy)
          GUID Alias: PERFEPP
          Minimum Possible Setting: 0x00000000
          Maximum Possible Setting: 0x00000064
          Possible Settings increment: 0x00000001
          Possible Settings units: %
        Current AC Power Setting Index: 0x00000000
        Current DC Power Setting Index: 0x00000000
    Power saver

    Code:
        Power Setting GUID: 36687f9e-e3a5-4dbf-b1dc-15eb381c6863
        (Processor energy performance preference policy)
          GUID Alias: PERFEPP
          Minimum Possible Setting: 0x00000000
          Maximum Possible Setting: 0x00000064
          Possible Settings increment: 0x00000001
          Possible Settings units: %
        Current AC Power Setting Index: 0x0000003c
        Current DC Power Setting Index: 0x0000003c
     
    Last edited: Dec 3, 2016
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