P870KM1 SLI "things".

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

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  1. cope123abc

    cope123abc Notebook Evangelist

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    I personally would remove ALL thermal pads for testing and drop on K50 PRO, this will eliminate any potentially raised thermal pads you are missing.

    If you are still in the same position after > Remove Shims > you said 1MM gap - that's a possible 24 degree increase... 90-24 = 66 degrees - this is what both my cards maxed out in SLI and others have reported the same temps, i really do suspect your issues are due to some sort of pad/VC damage.

    If it's still the same then I agree with @Meaker@Sager - sounds like the vapour chamber has failed.

    You can get a brand new 1 now for the KM1 for around £140 i think.

    Your running a CPU TM heatsink, so I am assuming you have had to mod your current KM1 heatsink somehow?

    Can you show us some pictures of the heatsink sitting flat on a table - to see if it's warped etc. Also the layout of it installed the laptop.
     
    Last edited: Sep 24, 2019
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  2. artpra

    artpra Notebook Consultant

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    I spent more than half a day for this and here are my findings:
    1. VC is perfectly flat, no warping no bents, totally symmetrical. When laid down on thick glass (as flat as you can get) there is no wobbling, it rests firmly on 6 copper plates which contacts with memory modules (via pad).
    [​IMG]
    Gap between glass surface and heatsink (where the GPU cores are) is the same for both master and slave card and it`s about 1~1,5 mm. All is great so far. Next!
    2. Cards outside the KM, secured with 8 screws to the VC, no pads on both cards - gap between both GPU cores and heatsink is exactly 0,5 mm. Yeah, nothing new here.
    3. Cards inside the KM, secured with 4 screws to the motherboard, 8 screws to the VC and with 4 screws to the frame, no pads on both cards - gap between cores and heatsink is (no surprise here) exactly 0,5 mm for master and slave. Next!
    4. Cards outside the KM, secured with 8 screws to the VC, pads being added one by one and inspected each time with flashlight (if there is proper contact with VC, not more than is need) until both cards are fully padded. Full success: pads are in place, all with proper height (fitted exactly for my VC sample). Gap between cores and heatsink is still exactly 0,5 mm for master and slave, so each and every pad is correct - they don't raise the VC at all. All good.
    5. Cards inside the KM again, secured with 4 screws to the motherboard, 8 screws to the VC and with 4 screws to the frame, with all pads on both cards in place (as in step 4) - gap between cores and heatsink is exactly 0,5 mm for master and slave. Bingo!
    6. It`s time to mount it, so: VC, Gelid, 0,5 mm pure copper shims (to precisely fill both gaps), Gelid, GPU cores. All good to go.
    7. Time Spy Extreme stress test, max fans (Fn+1), monitoring log start and...
    [​IMG]
    Red is master, green is slave. They are hitting 90C and throttling like before (that`s why I ended stress test at 13 minutes, there was no point to run it further). But there is some progress - previously it taken 10 minutes to reach 90C now it takes 12. And pads are proper for sure - there was no black screen (board is properly cooled).
    Hurrah, whoah, fanfcukingtastic!
    [​IMG]
     
  3. cope123abc

    cope123abc Notebook Evangelist

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    I would be really careful dude, those cards are hitting 90 degrees, that's way too hot for them in my opinion.

    Can you upload some pictures of your thermal pad layout you are using on the cards - with an edited pic of each width of every pad?

    I really cannot see it being anything other than thermal pad layout or vapour chamber compromisation.

    Have you modded your KM1 heatsink, i am assuming so as your running a TM heatsink ( show us pics )

    I personally never ran copper shims with my VC, why do you need the shims bro ?
     
  4. aarpcard

    aarpcard Notebook Deity

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    I'd like to chime in with some of my experiences. I've been fighting a very similar issue for a while. Laptop is in my sig.

    Some background. After first getting my laptop I flashed modded vbios's which raised the TDP limits of both cards to 250 watts. I repasted with liquid ultra and installed thinner thermal pads (0.5mm for vram, 1.0mm for chokes, 3.0mm for mosfets). GPU's were set in afterburner to 120% TDP with a 155mhz core OC and a 500mhz mem OC. Master was undervolted to 0.975V and slave was undervolted to 0.9625V.
    Everything was thermally stable long term in games. I mainly play the Witcher 3 maxed out with mods at 4k 60hz which results in 80-95% load on the cards. Thermals never went above the low 80's for several months.

    After a few months temps started to creep up to the point where the cards started bouncing off the 92C thermal limit. I figured maybe the liquid metal dried out so I repasted with new liquid ultra, and cleaned the fans/radiators thoroughly. This resulted in no change in thermal performance. Next I tried lapping the VC which resulted in atrocious performance due to presumably uneven levels between the two contact patches.

    I bought a brand new VC and installed it with liquid metal. No change in thermal performance. Still bouncing off the 92C limit. I attempted to solder additional fin stacks to the radiators and popped the VC.

    I bought another brand new VC and did the following:
    -Instead of lapping this one, I chemically polished the surfaces with a mild acid and NaCl to ensure only the smallest possible amount of material would be removed (probably just a few atoms thick). The polish came out great - similar to OP's pics above.
    -I next applied thermal Grizzly Conductonaut to the VC contact patches and let it sit for 2 days in a dust free environment so the gallium could oxidize into the copper as much as possible.
    -Then I applied more Conductonaut VC and installed the VC into the laptop with a very thin foam dam barrier to prevent Conductonaut from escaping and to minimize the amount of Oxygen present to react with the gallium/copper.
    -At the same time I also did a backplate retention mod on both 1080's to significantly increase contact pressure.
    -I also used thermal epoxy (instead of attempting to solder) to attach additional fin stacks to the VC radiators to take advantage of the open gap where the fans blow over the tops of the existing radiators.
    -I then removed all of the metal and plastic grates from the bottom and rear of the bottom bottom cover. The fans, VC, and radiators are all 100% open to the outside environment.
    -And finally I purchased a 100CFM laptop cooling pad.

    What's the final result? Peaks to about 82C under heavy load, with averages in the mid 70's. Not great at all considering the original heatsink with no mods other than liquid Ultra and thinner thermal pads managed the same thermal load at about 80C for months . . . until something changed.

    I also attempted to run with no thermal pads, except for 2.0mm pads on the mosfets and Thermal Grizzly Kryonaut on the chokes and vram chips to further increase contact pressure. The difference was negligible. I ultimately went back to the thin thermal pad configuration because I wasn't too comfortable with the contact patches for some of the vram chips. Do vram chips need significant cooling? I know on a lot of cards - desktop and mxm, they are not cooled or barely cooled.

    This has been an extremely frustrating, expensive battle which has gone on for almost 6 months. What can be done to definitively get these cards under control?

    What would the SLI cable have to do with temperatures?
     
    Last edited: Sep 24, 2019
  5. Meaker@Sager

    Meaker@Sager Company Representative

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    The ram making contact helps as there is no incidental airflow.
     
  6. artpra

    artpra Notebook Consultant

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    Pads are 100% proper, there's no doubt. Spent many hours on them, inspected each one, experimented with different thickness until I've found such configuration that touches VC properly and doesn't make the 0,5 mm gap any larger.

    How can I check if my VC is empty or not functioning properly (except, well - my temps lol)? Maybe it really is broken.

    I'm not using KM VC at all, I'm using TM variant. No mods whatsoever, brand new, straight from the box in to my KM1.

    I'm using shim because there is 0,5 mm space between VC and a GPU core - even without any pads in place, "naked" cards and VC aren't making proper contact. Without shim temps are even worse. But let's assume that shim isn't needed and should be removed. Keeping it wouldn't still be the reason of such high temps: it would result in great core temps and sudden black screen due to overheating card components (not touching VC because of unnecessary 0,5 mm lift caused by shim).

    Something else is going on, dunno.
    Is it possible that KM VC is SO MUCH better than TM one?

    @aarpcard I feel your pain mate, stay strong!
     
  7. cope123abc

    cope123abc Notebook Evangelist

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    The TM vapour chamber is better than the KM1, maybe you do have a defective VC.

    Your cheapest option is to buy another and test, those cards shouldn't get to 90 for 10 minutes, you will end up burning 1 out and costing you a small fortune bro !
     
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  8. artpra

    artpra Notebook Consultant

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    @aarpcard already tried this way and ended with zero improvement but another VC is the only solution I can think of.

    Anyone here have a spare TM VC? I would like to borrow it for short, non harmful test. :D
     
  9. cope123abc

    cope123abc Notebook Evangelist

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    I can't see what else it can be guys, sorry but your eyes would struggle to see a 1mm gap under a heatsink when its mounted.

    You would need to use pressure tape.

    It has to be some contact issue =)
     
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  10. aarpcard

    aarpcard Notebook Deity

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    I'm going to get a hold of some pressure paper and see what that reveals.
     
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