Zbook 15 G6 i9 model power limits

Discussion in 'HP Business Class Notebooks' started by martin778, Feb 10, 2021.

  1. martin778

    martin778 Notebook Consultant

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    Hi guys,
    I was wondering if anyone here runs a 15 inch Zbook G6 with the 9880H and what your CPU power limits are?

    My Zbook was working perfectly but since about 1.5-2 months it got very problematic, on battery the CPU locked itself to 1100MHz and wouldn't move, 15W power limit and no more. It would also shut down randomly on battery when presented with any CPU load. Even with the charger on it looked like it was somehow locked to 25W, the CPU speed dropped to 1800MHz.
    It ran so well for about 10 months and then it like suddenly 'lost it's mind'.

    Sent it back to RMA, HP replaced the battery and it's still the same, except that it doesn't shut down on battery but any synthetic/AVX benchmark makes the CPU go to 101*C instantly and stays there until it drops to PL1 and on battery it's still limited to 1100MHz/15W making it pretty much useless on battery except for office tasks.

    When on 230V power and running sustained GPU+CPU load, the CPU eventually drops to 1.4GHz and stays there, hampering the GPU.

    I have no idea what to do with it anymore, it won't fit in the toilet bowl to flush it...:oops:
     
    Last edited: Feb 11, 2021
  2. Charles P. Jefferies

    Charles P. Jefferies Lead Moderator Super Moderator

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    I would start by repasting the CPU with something like Arctic Silver 5. This could help your temperatures ...improves the contact between the CPU and the heatsink.

    Also, try undervolting with ThrottleStop. If you can't undervolt, at least you can tune the turbo power limits. I had to drastically reduce them on my EliteBook because the CPU would consume too much power and overwhelm the heatsink quickly.

    ThrottleStop will also help you diagnose exactly what is going on with the CPU ...it will list reasons for throttling (power, thermal, etc.). The Core i9-9880H should at least hit 45W under load, that is its TDP.

    Charles
     
  3. martin778

    martin778 Notebook Consultant

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    Hi Charles, the laptop has been repasted numerous times, last time I went all out and went LM on the CPU and GC Extreme on the GPU as for the latter there was not much difference in die temperature.
    I can't undervolt anymore (HP patched it) but the Power Limit of the CPU is weird, PL2 is variable - it's at 107W for the first couple of seconds, then 50W and after a minute it drops to 25W causing the CPU to go 1.4-1.6GHz on all cores. If I stop the stress test, the PL1 will reset itself to 50W again after a few seconds.
     
  4. AndreaM

    AndreaM Notebook Enthusiast

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    Did you check the limit reasons within ThrottleStop?
    About undervolt, are you able to downgrade the BIOS to known working prior version?
     
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