Warning: Some i7-6820HKs and i7-6700HQ have Uneven Core Temps due to Uneven Heatsink

Discussion in 'Hardware Components and Aftermarket Upgrades' started by iunlock, Oct 25, 2016.

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Does your 6820HK have cores that are 5c or higher than the others?

  1. Yes, I have a 6820HK that has 1 or more cores with a high temperature differential, greater than 5c.

    12 vote(s)
    9.0%
  2. Yes, I have a 6820HK that has 1 or more cores with a high temperature differential, greater than 10c

    16 vote(s)
    12.0%
  3. Yes, I have a 6820HK that has 1 or more cores with a high temperature differential, greater than 15c

    9 vote(s)
    6.8%
  4. Yes, I have a 6820HK that has 1 or more cores with a high temperature differential, greater than 20c

    23 vote(s)
    17.3%
  5. My 6820HK core temperatures are all tracking the same, with less than 5c difference.

    18 vote(s)
    13.5%
  6. Yes, I have a 6820HK where Core #3 (4th Core) is 10C cooler than the rest.

    1 vote(s)
    0.8%
  7. Yes, I have a 6700HQ that has 1 or more cores with a high temp differential, greater than 5c.

    10 vote(s)
    7.5%
  8. Yes, I have a 6700HQ that has 1 or more cores with a high temp differential, greater than 10c.

    15 vote(s)
    11.3%
  9. Yes, I have a 6700HQ that has 1 or more cores with a high temp differential, greater than 15c.

    8 vote(s)
    6.0%
  10. Yes, I have a 6700HQ that has 1 or more cores with a high temp differential, greater than 20c.

    8 vote(s)
    6.0%
  11. My 6700HQ core temperatures are all tracking the same, with less than 5c difference.

    11 vote(s)
    8.3%
  12. Yes, I have a 6700HQ where Core #3 (4th Core) is 10C cooler than the rest.

    2 vote(s)
    1.5%
  1. iunlock

    iunlock 7820HK @ 4.7GHz [LHz]

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    Is the issue bigger than just the tension arm on the new AW's? Find out here...


    ***News Flash!***


    The proof that supports my original theory of the heat sink being uneven due to the thermal pads being too thick on the FET's above the CPU is true. You'll have to use a thinner thermal pad to allow the heat sink to seat properly.

    Update (2-26-17): After analyzing numerous Heat Sinks, the culprit is in the design of the north part of the CPU plate. It bottoms out over the 'chokes' and causes the heat plate to sit at an angle which makes Core 0 and Core 2 temps much higher than the other two cores. Such a shame... It can be fixed, but it takes a lot of work to get it right if you want close to even core differentials.

    There is another issue though in that the north side of the CPU plate with having only one screw, does not provide as much support as the south side that has two screws. A tri-mounting design is nothing new and it could have worked out more efficiently if the die was centered.

    I've used some high end pressure paper...(This stuff is expensive.) Commercial grade stuff...

    - And guess what? The side that is not sitting flush so happens to be on the side of the CPU where there is only one screw whereas on the other side there are two screws LOL. Coincidence? I don't know...let's ask a chimpanzee. :p Not rocket science.

    So guys...there ya go...non-mystery solved. It's not the 6820HK...

    The 15R3's that I've been working on also has a core differential of 30C! I have ran a bunch of stock benches to collect stock data, which I do on all machines that I work on before performing the repaste. I'll report back with the post repaste temps when finished.

    Hope this helps those of you with the 15, sleep at night..

    Bottom line. Let Dell to take care of this issue. As I've said before, the ONLY reason you would want to keep your unit is if you have a nice silicon and ONLY then would you want to give it the time of day to fix the issue on your own to keep that mobo. Otherwise you're just doing an injustice to the situation that is factually common and evident among many many 15 owners. ie.....They are listening and will take action in addressing these issues.

    This type of QC issue should not exist in a $2000-$3000 machine. It's obviously the QC issue overseas and the poor workmanship that is being done there. Maybe Dell needs better management, an eagle eye on these workers and to switch up the thermal paste while at it.

    Everything else is beautiful...the machine is great, but some of the things under the hood prevents this great machine to work like it's suppose to. But that's being addressed so hang in there.

    Foundation is key and having good thermal paste along with a flush heat sink -> die to dissipate this heat is obviously important.


    Solution for Customers: What should be done on Dell's part: A conditional type of a Recall of the AW15R3/AW17R4 and provide 1st Class service to those who have been affected. Fair is fair. ie... If a customer complains about their temps then take care of them right away.

    Solution to fix the issue at the Factory: Perhaps make that single tension arm on the CPU side flat instead it being bend at a 90 degree angle near the screw. Check below, 9th picture down. Also, change out the thermal pads to a thinner one that sits over the FET's above the CPU. I've already tested this and it works well in conjunction with the bending of the tension arm.

    Hope this helps...

    It's obvious that it's cooking under there...look at that...
    [​IMG]

    See those bubbles?! Air bubbles / pockets from the stock paste or any paste = NO GOOD! HEAT!
    [​IMG]

    Laying down the pressure paper...
    [​IMG]

    See how much darn pressure is on one side? Just crazy... (This is the CPU side.)
    [​IMG]

    Evidence that the heat sink is uneven. Look at what side the pressure (red area) on the GPU is...yup... Also, the GPU has way more tolerance than the CPU although it is uneven like this, which is why the GPU temps aren't really an issue with a good repaste.
    [​IMG]

    Plus look at them grooves on the CPU side of the heat sink! SMH ...This is why I lap the heat sink. Yes really... :)
    [​IMG]

    ***A Solution to fix the issue.***


    On the CPU side of the heat sink plate there are three screws. One up top and two on the bottom. What you'll want to do is carefully bend the top tension arm upward so that when you tighten the screw in it'll create more pressure on that side of the heat sink plate, in hopes to even out the pressure of the heat sink against the CPU die. Also, use thinner thermal pads on the FET's above the CPU so that the heat sink can sit flush, thus providing a more even contact between the CPU die and HS.

    [​IMG]

    WARNING: Avoid trying to loosen the two bottom screws to compensate as this is not the best option nor will it work as I've tested this already. All you'll be doing is creating a uniform GAP, which is not good for most thermal pastes due to its viscosity, let alone liquid metal! This is disaster waiting to happen. Pump out anyone? 100% pump out unsatisfaction guaranteed.

    In some cases it may work, but if the pressure on one side of the CPU die is really bad and if there is no pressure on the opposite die of the CPU, it is counter intuitive because then you'd just be making an even space above the CPU die. This may work in the event of using a thick paste, however, having a gap between the CPU die and heat sink is not ideal for laptops.

    [​IMG]

    Be careful not to bend it too much. -- (Here's the 9th picture. See the 90 degree turn at the tip of the tension arm? Instead of having it bent like that, perhaps make it straight so that when it is screwed into place, it'll provide more tension.
    [​IMG]


    Thanks @hmscott for all your great posts. I'm also glad to be of help.

    -

    Although the purpose of this thread is NOT about REPASTING as a solution, the pictures below are for your viewing in hopes to satisfy any recommendations of respasting so that it is not mentioned. So please soak it all in. :p

    Take a look at stock paste from my 17R4 lol...just crazy right? Spend all this money on R&D only to end up using crap paste? Yikes...Well numbers don't lie so I challenge anyone to put it to the test. The proof is in the pudding.

    (These are from my repaste guide that just went live yesterday.)

    [​IMG]

    [​IMG]

    [​IMG]

    ---

    On the bright side with a little work under the hood you can have the complete package.

    ***11 HOUR OCCT RUN on the 15R3***

    EXTREME TEST!


    Look at the temps! Max and Average.
    • Liquid Metal Magic: Grizzly Conductonaut
    • Thermal Pad Replacement: Fujipoly 14.0w m/k
    • Realignment of the top tension screw on the CPU side of the heat sink. Click here.
    • Lapped Heat Sink.
    • Polished Everything Squeaky Clean.

    6820HK Stress Test. PASS.
    [​IMG]

    -

    15R3 with STOCK TOOTHPASTE and STOCK CLOCKS. FAIL.
    [​IMG]

    Thanks to @Mobius 1, @DeeX, @zergslayer69, @hmscott and everyone else that is contributing in providing valuable data!
     
    Last edited: Feb 27, 2017
  2. iunlock

    iunlock 7820HK @ 4.7GHz [LHz]

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    Here is the repasting solution just to get it out of the way so we don't flood the rest of the thread with, "You should try and repaste.":

    Okay so here's my take on the whole 6820HK issue. From my experience anytime the temps were off by a lot on some of the cores, it was almost always due to there not being enough paste on the die. The core order is kind of like the firing order on an engine so 0 is diagonal from 3 and 1 is diagonal from 2.

    It could be that the heat sink is warped to where it is only making good contact across the die, diagonally, which is causing cores 0 and 3 or 1 and 2 or heck even 0 and 2 depending on which angle the uneven contact of the heat sink lies.

    I would try repasting and using a healthy amount of paste to make sure that you have a nice thick even layer on there to ensure even coverage and to test the temps again. If the two cores are still miles apart from the other two, then it's likely a hardware issue. Also, just so we're on the same page, make sure that you're setting all the multipliers to the same number, ex. 36x on all four cores...

    Another thing to try is to go into BIOS, set everything to defautl/factory stock, restart and enter BIOS again. -> Then make your changes on the OC profile or whatnot and reboot. Often times if you just set your settings without bringing it back to default, it can act very strange....BIOS is weird to begin with so it's good to make it a habit of always setting it back to default first, restart and to re-enter BIOS again on a fresh clean slate. Hope that makes sense..

    Also.....I did notice something strange on the die of my 6820HK yesterday when repasting it. There seem to be a little bubble on the die that was underneath the surface? Let me see if I have a pic of it....but it could be possible that there are defected batches of these chips? Who knows....so far everything seems fine though temp wise. All my cores are pretty even and sometimes exactly even...
     
    Last edited: Oct 25, 2016
  3. iunlock

    iunlock 7820HK @ 4.7GHz [LHz]

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    Toothpaste Hall of Fame:

    Share your pics so we can let it be known!
     
    Last edited: Oct 25, 2016
  4. iunlock

    iunlock 7820HK @ 4.7GHz [LHz]

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    AW17R4 - 6700HQ Stock.

    Although we're focusing on the 6820HK, the over heating issue with AW is across the board even with the 6700HQ. (Mostly due to the thermal paste and uneven heat sink issue, but still...6700HQ or 6820HK, it doesn't matter.)

    [​IMG]
     
    Last edited: Dec 7, 2016
  5. mason2smart

    mason2smart Notebook Deity

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    I had an issue like this with my gt80s before xotic PC shipped it, I had them paste with clu which made the issue exponentially worse ~20 C difference. I got them to build me a new laptop from scratch and this one still gets a 10 C difference but rubs on stock paste
     
  6. ryzeki

    ryzeki Moderator Moderator

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    Issues with uneven cores seem to be releated to heatsink issues making uneven contact. Part of the issue can be alleviated slightly by adding a bit more paste, but it does sound, to me, like hardware defect.
     
  7. keftih

    keftih Notebook Evangelist

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    That would be a massive defect :eek:
     
  8. iunlock

    iunlock 7820HK @ 4.7GHz [LHz]

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    That rules out the paste then? I had a feeling that it could be heat sink related...interesting...

    Yes, Liquid Metal would make it worse with it being liquidy on a warped heat sink...

    Correct. I always recommend being more generous with the paste with laptops due to the low pressure mounting vs a desktop where it has much more pressure so the amount of paste used isn't as important. However, with cases of uneven heat sinks and improper contact, compensating that gap by using thicker paste like ICD (which I'm not a fan of) wouldn't be the best option in my opinion. It'd be best to correct the underlying issue.

    Yes it would. This is an issue with some of the Clevo's ...what a nightmare. - And sure enough the resellers use ICD to compensate for the warped heat sinks, gap etc....SMH....
     
  9. pat@XOTICPC

    pat@XOTICPC Notebook Prophet

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    It's entirely possible it could be related to the heatsink, if there is any warping. It was one possibility we considered looking at, but ended up switching systems as mentioned.

    Well, it is used just because it is just a better paste than a good amount of other brands out there. (Not saying it is always the best, but just in general it has decent temp drops on just about any computer)
     
    Papusan likes this.
  10. hmscott

    hmscott Notebook Nobel Laureate

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    We all know repasting is often helpful when you get a laptop shipped with bad paste or a bad paste job.

    That's not what we are talking about here. :)

    We are talking about hot cores in a CPU from a pressure imbalance with the heatplate.

    We have recently run across several 6820HK's that have at least 2 cores 10c-15c-20c hotter than the other 2 cores.

    This is a heatplate pressure imbalance that re-pasting better or with better paste has no effect except to lower the overall temperature across all cores - the core temperature differential isn't affected unless you balance the heatplate pressure on the CPU evenly.

    To warn new 6820HK owners with high core temperature differentials from re-pasting, and to instead return their laptop for another unit to get a better fitted heatplate.

    We have a couple of new examples that can be used to help the new owner recognize the problem, and @iunlock is in the process of setting that up.

    For now, please refrain from making re-paste recommendations for 6820HK owners with a couple of hot cores in this extreme differential range: 8c-10c as high as 20c, it won't help without also balancing the pressure applied to the heatplate over the CPU. :)

    Edit: Edited to remove CPU failure possibility, as the uneven heatplate pressure imbalance has been found to be the issue causing the uneven core temperatures.
     
    Last edited: Nov 11, 2016
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