P870KM1 SLI "things".

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

  1. artpra

    artpra Notebook Consultant

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    I recently bought a second 1080 for my KM. My setup is as follows:
    - KM1 flashed with stock TM BIOS and stock KM ECs,
    - 9900K,
    - TM CPU heatsink,
    - TM GPU vapour chamber,
    - Two 1080,
    - AUO B173HAN03.1 screen running at 144MHz.

    First thing I noticed after mounting second 1080 was high temps (~50C) and fan noise while doing „non 3D” regular things (web, office etc). After inspection I saw a very high GPUs utilization at idle, even on desktop. Both cards almost never properly sleeps at lowest P state and 139MHz clock. When I open one tab (!) in Chrome (no fancy stuff, just plain text web page or something light like this forum) and scroll it up and down fast, both cards goes to 1511MHz clock (!!), shows 40~50% 3D utilization (!!) and eats 40W each (!!!) and both fans starts to ramp up. It`s insane, 80W just to display a fast scrolling letters!

    I`ve never noticed this with single 1080 but it doesn`t mean that it wasn`t happening. So I don`t know if this behavior is SLI specific (and that`s why I noticed it only now) or general 1080/Pascal/nvidia issue (single 1080 was the same but vapor chamber cooled it well enough that fans stayed quiet and I never noticed).

    Interwebz lecture says that is normal, and that`s a cost of feeding 144MHz screens but those reports mainly focuses on multiple displays configuration. That I can believe (much more screen pixels to handle) but in one 144MHz screen scenario it looks like some serious bug in nvidia drivers.
    It`s driver and Windows OS agnostic, happens here with 38x.xx/39x.xx/4xx.xx and Win7/10 combinations.

    Can you confirm it being normal with yours 144MHz+1080 SLI setups?

    To avoid that, I found two solutions:
    - switch screen to 60MHz refresh (120MHz is the same as 144MHz) and everything is back to normal, cards idles at 139MHz clock, web browsing won`t wake them, fans stays quiet, all is fine but… 60MHz
    or
    - stay with 144MHz and block both cards in P8 state with nvidia inspector and add 3D programs/games to the exclusion list (threshold setting didn`t work for me) which is only a minor inconvenient for having 144MHz with proper (cool and quiet) idle operating.

    [​IMG]

    Is there anything more, another solution to this issue?


    Also I would like to hear your opinions about cooling efficiency, some „audit” from others with TM VC and 1080SLI.
    I always aims to stay at stock clocks/turbos but to undervolt GPU as much as it`s stable.
    So master card is undervolted to 0,925mV
    [​IMG]

    And slave is undervolted to 0,900mV
    [​IMG]

    Cooler running card (lower voltage=lower wattage=lower temps) is on purpose put in the slave slot which is harder to cool.

    Vapor chamber is polished like that:
    [​IMG]
    [​IMG]

    For both GPU I needed to use 0,5mm shims because of 0,5mm gap (precisely measured – that`s the reason I couldn`t use liquid metal), shims also polished but not so much:
    [​IMG]

    Thermal paste used – Gelid Extreme.

    Now on to testing. Stress test with Time Spy Extreme so cards were slammed hard constantly for 20 minutes (max fans, 22C ambient).
    Master peaked at 175W and slave at 180W but 90% of time they were in 155-160W range:
    [​IMG]

    As for temps, master peaked at 90C and was flicking between 89-90C constantly. Slave peaked at 91C and stabilized with 90C flat:
    [​IMG]

    Both cards started to throttle at around 10 minutes of test - clock was flipping from 1657,9MHz (lowest) to low 18xxMHz. They throttled still stayed in highest P state and turbo range:
    [​IMG]
    [​IMG]

    For reference, the same stress test in the same conditions and configuration (shim, gelid, max fans, 22C ambient, etc) BUT with single card (master one, that „hotter” running at 0,925mV) gives me 63C max – no benchmark loop can bump its temperature higher and it was (is) great, with SLI it`s not so great anymore (or is it?).

    So this temps are normal and typical for 1080 SLI?
     
  2. clevo-extreme

    clevo-extreme Company Representative

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    Normally yes. But it can be sli cable issue. What is the number from sli cable?

    Fastest Customizable Gaming Notebooks & Mobile Workstations | CLEVO Integrator
     
  3. artpra

    artpra Notebook Consultant

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    It`s 6-43-P8720-010 and it`s fine I`m sure.
     
  4. Meaker@Sager

    Meaker@Sager Company Representative

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    Your polishing will have also created more of a gap, with the right thermal pad layout liquid metal use is possible.
     
  5. artpra

    artpra Notebook Consultant

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    Measurement was done after polishing, it`s 0,5mm for both GPUs. Gap is the same even without any thermal pads in place so with liquid metal applied contact (and heat transfer) is terrible. I`ve tried.
     
  6. Meaker@Sager

    Meaker@Sager Company Representative

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    Was that measurement done outside the case?
     
  7. artpra

    artpra Notebook Consultant

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    Inside, with both cards in MXM slots and secured with screws and with vapor chamber fully mounted (all screws in place).

    So what, polishing/gap/liquid metal aside - temps should be lower?
    I'm reading TM1 1080 SLI reviews and they showed even worse temps (with stock everything so it looks correct).
     
  8. cope123abc

    cope123abc Notebook Evangelist

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    I would say those GPU temps are WAY 2 high.

    To give you an accurate idea, that card you purchased from myself, wouldn't exceed 65 degrees under load in SLI when sitting on LM that was with both cards sitting on +550 memory and boosting up to core 2088 which they were stable at and passed all tests.

    I would agree with @Meaker@Sager that you have a gap there.

    From personal experiance a small gap even 0.5mm will create 12 degrees onto temps straight away ( i think this is right - going from @Meaker@Sager info) when he helped me on my watercooling build.

    You shouldn't be getting more than 65-70 in SLI in my opinion if using LM and everything is touching correctly.
     
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  9. cope123abc

    cope123abc Notebook Evangelist

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    Also it should be hitting 200 watts ! it's thermal throttling here dude, you have an issue with contact i would say.
     
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  10. jc_denton

    jc_denton Notebook Evangelist

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    I'd listen to brother cope here, the whole contact issue is fresh in his memory :)
     
    Papusan and cope123abc like this.
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