Surface Pro 4 i7-6650U power throttling issue?

Discussion in 'Microsoft Surface Pro 4' started by theveterans, Nov 24, 2015.

  1. theveterans

    theveterans Member

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    I have a friend who wants to get the Surface Pro 4 i7 model after seeing my SP3 i5 without throttling issues when running CPU & GPU intensive games. However, while browsing on YouTube to look for SP4 i7 gaming performance, I saw a video that shows how SP4 throttles to equal or worse than Core M3 performance when CPU and GPU are pegged to the max due to the 15W Package (not core) limit per video shown below:



    Is anybody experiencing the same throttling issues with their i7 SP4 when gaming?

    PS. I notice that Intel dropped the Package Power limit to 15 Watts in Skylake as shown on the video where it was 19 Watts for Haswell (15 Watts for CPU core TDP though). Below is the screenshot where my SP3 i5 runs at 15 - 19 Watts of power during CPU and GPU intensive games. Turbo Boost turns off automatically (1.9 GHz base clock) to allocate power to the HD 4400 GPU so that it is always maxed out at 1 - 1.1 GHz and no FPS drops whatsoever on Asphalt 8 game and CS GO.

    [​IMG]
     
  2. theveterans

    theveterans Member

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    I might also add that undervolting using Intel XTU isn't a good solution to this because it pretty much kills sleep and connected standby. Also, no casual people (not tinkerers) would even dare to undervolt the CPU.
     
  3. leeshor

    leeshor Well-Known Member

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    Many people, like me, for instance, only care that my i5 has done everything I have asked it to do in fine fashion. Has it throttled, maybe, maybe not. I haven't noticed. It's doing a great job.
     
  4. theveterans

    theveterans Member

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    Agree too. Not much of a gamer myself, but not throttling (i.e. CPU package power consumption doesn't go below 15 Watts) is a good bonus for me.
    I would gather more responses and data, and if this Core i7 power throttling issue is widespread across many users, I would let him know to avoid the i7 model and go with m3/i5 model where it doesn't throttle like my SP3 i5. No point for i7 + iris 540 GPU if it can't game consistently. BTW, my SP3 i5 gets 60 - 100 FPS consistently on the CS GO game featured on the video (low-medium settings), even after playing for 2 hours straight. When I quit the game though, my battery went from fully charged to 91% (after 2 hours of gaming). It seems that SP3's firmware is smart enough to steal power from battery if the system needs more power than what the power brick can provide. My speculation is that Microsoft probably configured the firmware to not draw power from battery or that Iris 540 GPU gobbles up too much power that the CPU can't get more power to keep the frequency high at very high sustained loads.
     
  5. GatsbyGlen

    GatsbyGlen Member

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    Why does it kill sleep?

    I see a setting called "Turbo Boost Power Time Window". My SP4 came with it at 1 second. XTU says the default is 28 seconds. I'm trying to understand what it means.

    "The time window over which the average CPU core power must be below the Turbo Boost Power Max."

    At first glance, does this mean a larger window will use less power?
     
  6. theveterans

    theveterans Member

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    I am not familiar with those mobile CPU settings. I do know that undervolting kills sleep and connected standby because during sleep/connected standby, CPU is put to C7 sleep state (maybe C8 in skylake chips) which is the lowest voltage applied to CPU. If you undervolt, you tell a specific CPU offset to decrease the CPU voltage by that amount. At the CPU's highest number C-state, it is at the lowest voltage where it can go back to C0 state or P0 state (turbo boost) Any lower than that will result to CPU power failure and your computer turns off abruptly. The moment you power on, the BIOS will initialize and Windows will say an error of unexpected shutdown. Everything You Need to Know About the CPU C-States Power Saving Modes - Page 6 of 7 - Hardware Secrets
     
  7. GatsbyGlen

    GatsbyGlen Member

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    Thanks for the info!
     
  8. the_new_normal

    the_new_normal Member

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    That's the time it will look at to measure average power. So at 28 it will review the last 28 seconds and if average is over power limit it will throttle.

    It's how responsive to change you want it.

    EDIT: quote fail, but you get the idea
     
    Last edited by a moderator: Nov 26, 2015
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  9. leeshor

    leeshor Well-Known Member

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    Quote issue more or less fixed. ;)
     
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  10. Seneleron

    Seneleron Active Member

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    Think about this one for a minute: In the video above, a person unlocks an extra high performance mode, and then complains when his system throttles in response to said high performance mode. There is no comparison video of the same thing happening with the STOCK power plan, so we cannot be sure if this is a design flaw or operator error.
     
  11. odyn

    odyn New Member

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    No, youre totally confused. He did not overclock it or anything remotely close to what you are implying. He shows the settings clearly, its just the battery saving settings, which are standard settings in the control panel.

    Going from battery saving to max performance isnt what it sounds like to the novice windows user. It just changes how soon the display goes to sleep and how dim the the display is. Its nothing remotely close to extra high performance, its more like standard performance if you dont care about battery life.
     
  12. theveterans

    theveterans Member

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    He is showing what most casual users do if they want to get high performance. Of course there are more extreme ways to get higher benchmarks/performance by undervolting etc.

    On some videos, power throttling i7 is still faster in gaming than i5 that power throttles less because many games are GPU dependent. However, if the game requires high CPU usage like CS GO, BF3 multiplayer, Need For Speed Hot Pursuit 2010, Blacklight Retribution, etc. i7 sp4 will perform worse than i5 and that of m3 level.

    I think this is a design overlooked by Intel. Iris GPU just consumes probably 25 - 50% more power than HD520 and because of the 15 W TDP (25 TDP for initial 28 sec boost), the iris 540 GPU can gobble up 10 W or more so there's only 5 W remaining for CPU and as such it'll downclock to 1.5 GHz or less to keep the power within that 5 W remaining. Think about this, if you max out the CPU only, it can consume the whole 15 W TDP just by itself. Maxing out the GPU (3D mark) consumes 10W or more watts by just stressing GPU only.
     
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