XPS 15 9570 Owners Thread

Discussion in 'Dell XPS and Studio XPS' started by el3ctronics, May 16, 2018.

  1. custom90gt

    custom90gt Doc Mod Super Moderator

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    The best way is to log your temps and clockspeeds with hwinfo to determine where it is throttling and what is causing it. If I recall correctly throttle stop showed PL1 throttling when the VRM got too hot and clockspeeds would go way down.
     
  2. Kretschmer

    Kretschmer Notebook Enthusiast

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    Curious to see how this throttles. My Ideapad 720S requires undervolting, too. You'd think that manufacturers would actually play some AAA games for an hour before locking in clocks and voltages.
     
  3. abujafar

    abujafar Notebook Evangelist

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    Ok, guys I have something.
    https://pastebin.ca/4029283

    I started analyzing this hwinfo trace. It's from a reddit user running RealBench stress test on a new computer with no mods (this is CPU/GPU combined stress test).
    It's clear that there is major perfomance drop.

    It seems that Turbo Boost Power Max Limit (PL1 limit) goes from 56W to 15W and with it the clock goes way down.

    (PL1 is the long-term turbo boost limit. While PL2 is the short term boost limit PL2>PL1).

    I do not know if this PL1 limit is managed locally by the CPU or if an outside agent (DELL) can set this value if some other component in the system are running hot (GPU, VRMs) or for battery savings.
     
    Last edited: May 29, 2018
  4. custom90gt

    custom90gt Doc Mod Super Moderator

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    PL1 can be managed by Dell and likely is. Sadly that log doesn't have the dell temp sensors enabled so you can't see what the actual temps are.

    Looking at the logs quickly I see that it is throttling the CPU and GPU quite a bit. My guess is that because it's doing both so drastically it is the VRMs running too hot. Sucks there isn't the Dell sensor logs, but if the CPU is at 15W and the GPU is down to ~400mhz it's probably not power limit throttling.

    On my 9757 the GPU speed is pretty constant and it will drop the CPU power consumption to ~20-25w to keep under the 45W limitation.
     
    Last edited: May 29, 2018
  5. abujafar

    abujafar Notebook Evangelist

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    From the graphs that I have done, the GPU clock is rock solid for the whole test duration (1645 Mhz). The CPU clock tanks heavily...

    @custom90gt I think you were looking at the GPU clock of the integreted gpu, not nvidia gpu
     
    Last edited: May 29, 2018
  6. seiyafan

    seiyafan Notebook Evangelist

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    Does m.2 Optane fit in this machine?
     
  7. custom90gt

    custom90gt Doc Mod Super Moderator

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    You're right, I was looking at the GPU clock for the igpu. So it could still be system level power limits, but that would be stupid to limit them both so heavily. Would need proper logs to verify though.
     
  8. abujafar

    abujafar Notebook Evangelist

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    I can understand that, but dropping to 15w (<1Ghz clock) is a lot. too much.
     
    Last edited: May 29, 2018
    custom90gt likes this.
  9. Eason

    Eason Notebook Virtuoso

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    Haha I always do benchmarks with tweaks! My XPS 13 iris review had a spin-off article where I just talked about repasting and pads!
     
  10. abujafar

    abujafar Notebook Evangelist

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    I did some more digging on the data. There seems to be something magical at the 80c threshold. When the CPU temp (or GPU temp, they are pretty coupled under sustained load) hit the 80c, a major PL1 drop happens.
     
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