P870KM1 SLI "things".

Discussion in 'Sager and Clevo' started by artpra, Sep 20, 2019.

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  1. aarpcard

    aarpcard Notebook Deity

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    At stock clocks and voltages, I'm averaging in the high 70's and peaking in the low 80's after mere minutes in game. Prior to all the mods I did, it would bounce off the thermal limiter within minutes. Boost throttles down to 1810mhz.

    This is my third brand new TM VC heatsink. All three have exhibited the exact same issues. What are the chances I got 3 bad factory new heatsinks in a row? I also know someone with a KM with SLI 1080's that has the exact same issues with the KM VC heatsink. Really the only way to tell for sure is with pressure paper (which I have on order), but I'm starting to question if it's an issue with the heatsink.

    What are the chances the chassis is skewed or the motherboard is skewed in the chassis resulting in the GPU dies being very slightly tilted in relation to the heatsink?

    Honestly while the VC is a very cool concept, it's execution in these laptops is extremely poor. If it's true that a 0.5mm gap would result in a 12C temp increase, then you have a ridiculous amount of dimensions that have to be toleranced to within thousandths of an inch to each other: The z-height of the both MXM PCB's, the pitch of both gpu die packages, the z-heights of the packages themselves, the z-heights of each mxm slot, the z-height of the motherboard, the z-heights of both contact patches on the VC, the pitches of the contact patches, the mounting points of the VC to the chassis, the chassis dimensions, all have to be ridiculously precise. They're all referenced to each other. Any one being off a hair will mess up the entire system.

    Even if I managed to track down what the offending dimensions are, I have absolutely no idea how I'd go about fixing them considering the level of precision required.

    A much better design would have been two independent VC heatsinks (one for each gpu) mounted directly to the MXM cards with no interface to the chassis or each other. In that setup the only dimension that would matter would be the flatness of the contact patch which could be easily machined. This is extremely frustrating.
     
  2. Meaker@Sager

    Meaker@Sager Company Representative

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    Possibly your posts either side are off, this is my second heatsink without issue.
     
  3. aarpcard

    aarpcard Notebook Deity

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    "Posts" being the MXM standoffs on the motherboard, or the places where the VC screws into the chassis? I suppose it could be both . . .
     
  4. Meaker@Sager

    Meaker@Sager Company Representative

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    More likely the chassis connection.
     
  5. artpra

    artpra Notebook Consultant

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    Guys,
    any input about high clocks/GPUs usage with 144MHz screen?
     
  6. Meaker@Sager

    Meaker@Sager Company Representative

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    Not on the latest drivers pushing two 1440p 120hz displays.
     
  7. yrekabakery

    yrekabakery Notebook Virtuoso

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    Should've been fixed in drivers years ago. Used to be that 144Hz would cause the GPU to stay in P0, only 120Hz and below would allow it to downclock unless Nvidia Inspector Multi-Display Power Saver utility was used.
     
  8. Meaker@Sager

    Meaker@Sager Company Representative

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    IIRC it came back during the RTX launch for RTX cards in the first driver packages?
     
  9. yrekabakery

    yrekabakery Notebook Virtuoso

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    Doubt it, considering most higher end gaming laptops since early last year ship with 144Hz panels, it would've been a widely reported issue, but it hasn't been.
     
  10. aarpcard

    aarpcard Notebook Deity

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    Figured I'd update this thread. I think I've solved my issues. I bought some pressure paper, but did not get around to testing the die contact patches. I'll probably due that the next time I need to do a repaste.

    However, I also bought some K5-Pro thermal Pad replacement: https://www.amazon.com/viscous-thermal-replacement-60g-Aspire/dp/B00K04D3UK

    This stuff is like a putty that you can form into the shape of thermal pads. It is viscous enough that it will not disperse like thermal grease, and it is formable enough that the pressure from the heatsink will force it to compress easily unlike thermal pads. I replaced the 0.5mm and 1.0mm thermal pads I was using on both cards with the K5-Pro. I did not replace the 3.0mm pads for the voltage regulators.

    Since doing this, at stock voltage and a 155mhz overclock, with both cards pegged at 100% usage in games, I've yet to see temps over 72C. Usually they sit in the high 60's. I guess the issue, (or a major part of it) was insufficient clearance between the heatsink and the components that require thermal pads. Back when I first got the machine, I changed out the stock pads for the 0.5mm and 1.0mm pads, and that improved temps significantly. Not sure why they degraded from there, but eliminating the resistance from the thermal pads fixed it.
     
    cope123abc and Papusan like this.
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