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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    Though general benchmark/programs cannot show the performance difference, some time-critical programs are very sensitive to the clock cycle. I had some issues when using an ARM processor simulator for it requires very precise clock cycles.

    In theory, SpeedStep and SpeedShift should not have impact on the CPU clock cycles. But once I turn of SppedStep and SpeedShift, the simulator becomes normal. It is really weird.
     
  2. pressing

    pressing Notebook Deity

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    New ThrottleStop software just released. Speed Shift upgrades include EPP monitoring real time.

    I don't know any other software that provies RELIABLE EPP monitoring (powercfg and control panel provide wrong data on the 9550). See below for details and link...


     
  3. ChristianDD

    ChristianDD Newbie

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    I notice that when I enable speed shift, I get less performance in gaming. During gaming I notice the CPU is not ramping up as high, but staying around 1.2ghz. If I set the EPP at 1, CPU stays too high, and 128 (default) gets me less performance in gaming.

    On the Surface Pro 4, EPP at 128 does not give less performance.

    Anyone else test this on gaming performance?
     
    pressing likes this.
  4. pressing

    pressing Notebook Deity

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    If you run EPP= 0 does that work better than EPP=1?

    Is the "EPP" indicator green in your ThrottleStop main window (or on HWiNFO 64)?

    Regardless, if you are driving CPU in extreme situations, SpeedShift benefits will be reduced as CPU will be spending a lot of time in C0 states so less "shifting is required.. .

    Disabling C-States in extreme situations might give the very best extreme performance. You can do that in the 9550's BIOS but I'm not sure that is optimal in such a thin laptop as the CPU may run hotter, providing less cooling capability for the GPU. Maybe not a safe option for CPU longevity. ThrottleStop does provide a checkbox to disable C1E states which I found to be hepful.

    Also disabling C-States and/or SpeedShift capped CPU frequencies on my i5 (I just can't remember the combination that was problematic).

    Intel guidance for laptops suggests EPP~128, which is a balance between performance and energy savings so performace with EPP=128 is probably too much different than a laptop without SpeedShift enabled.
     
  5. Techland

    Techland Notebook Consultant

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    Hmm, now that is astonishing. I updated two BIOS versions since I turned on SpeedShift, and HW Info still shows green. I would have expected that a BIOS update overrides those changes and resets SST to off...
     
  6. goodwin_c

    goodwin_c Notebook Enthusiast

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    Until you will do factory reset - SST will be enabled. In theory, bios factory reset should change it back to disabled state, but i wan't try it.
     
  7. pressing

    pressing Notebook Deity

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    I think this is not correct with the Dell 9550.

    On my 9550, restarting has always disabled SST (as long as I don't run ThrottleStop or have SpeedShift options disabled in ThrottleStop).

    To verify, one can see that in the HWiNFO64 screen as the letters "SST" are red when SpeedShift is disabled and green when SpeedShift is enabled.

    From ThrottleStop developer:

     
  8. Techland

    Techland Notebook Consultant

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    Of course it survives reboots - if you use the EFI shell to type in the 0x1 command, like I did.
     
  9. pressing

    pressing Notebook Deity

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    That's true! You would need to take that out
     
  10. ChristianDD

    ChristianDD Newbie

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    Yes EPP is green. When running EPP=0, it's basically like running in High Performance mode, so any battery benefits will be negated. I'm still testing how batter life is on EPP=128. CPU ramps up fine during usual operations, but for some reason while playing a game like Overwatch, CPU doesn't ramp up that high.

    Are others really benefiting in battery life and responsiveness from Speed Shift on our Dell XPS 15?
     
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