XPS 15 9550 temperature observations (undervolt + repaste)

Discussion in 'Dell XPS and Studio XPS' started by custom90gt, Dec 28, 2015.

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  1. pressing

    pressing Notebook Deity

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    Typically, how would you expect the heat of the CHOKES (6xMagicTec R22) compare to the heat of the MOSFETS (3xTI 873510 & 3xAO ZS019QI)?
     
  2. GoNz0

    GoNz0 Notebook Prophet

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    I will let you know if my none contact probe arrives!
     
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  3. pressing

    pressing Notebook Deity

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    That probe is lost in the post!

    Sorry for repeating detailed elementary questions. I ask as I thought MOSFETS were generally heat generators and very sensitive to heat, whereas chokes are typically just wound wire which don't generate much heat and are not too sensitive to heat...
     
  4. custom90gt

    custom90gt Doc Mod Super Moderator

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    So sadly I don't have thermocouples or even a cheap temp gun to check so here is why I decided to sink the chokes.
    1. With the case open and the system on, they were the hottest things to touch within the first couple minutes of powering it on.
    2. They are tall enough to easily be sinked to the bottom of the case.
    3. I don't have time to make copper shims for the MOSFETs

    After running 8 loops of Time Spy the max VRM temp was 68*C - down from 78*C after only 2 runs of Time Spy.

    The bottom of the case was not significantly warmer and thus far I have not experienced any changes in fan duty cycles.

    I do welcome anyone here to try sinking their MOSFETs or coming up with other ideas. Sadly I don't think I have thick enough thermal pads to sink them (also that's quite the distance, the thermal conductivity would likely be poor anyway).
     
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  5. einsteinchen

    einsteinchen Notebook Geek

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    @custom90gt could you post a picture of where and how you placed the thermal pads on the sensor? I am aware of the drawing posted earlier here, however I would feel safer if I could see an actual image of the pad application.

    Regarding the actual VRAM temps: I replaced the stock pads with 'Alphacool Eisschicht' pads, they claim to have 14 w/mK. Eisschicht is a german word and means icesheet, or layer of ice. My first tests (playing Dota2 for at least 30 minutes, that is also how I recorded the temps posted earlier) show only a minor improvement when comparing 'Ambient' temps from before to the new pads, around 1 to 4 °C. One could argue, that this makes no difference when considering room temperature and margin of error. However, I will investigate this further.

    @Brian Anderson when I was playing Dota2 on my XPS yesterday ans had HWInfo64 open on a second screen. Flowing gently down behind F7/F8 reduced the 'Ambient' temps also for me by ~10 °C accodring to the temps reported by HWInfo. Just to confirm your findings :) Good Job!
     
    Last edited: Sep 9, 2016
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  6. custom90gt

    custom90gt Doc Mod Super Moderator

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    I only put thermal pads on the larger R22 chokes. I can take a picture later today after I get out of school, but if you look at the picture on page 27 you can see the large grey R22s.
     
  7. einsteinchen

    einsteinchen Notebook Geek

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    Thanks for the page number! This makes it clear for me where to put the pads, I guess. Just to be safe, you mean the the ray square things I marked green? I hope GoNzO does not mid that I alterd his image ^^

    http://imgur.com/U4qgbLp
     
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  8. custom90gt

    custom90gt Doc Mod Super Moderator

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    Yeah that's where I put them because it was the easiest thing to sink. Nothing weird has happened yet, they are constantly cooler for me and I don't have any real change in the temp of the bottom of the laptop.
     
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  9. GoNz0

    GoNz0 Notebook Prophet

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    [​IMG]
     
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  10. pressing

    pressing Notebook Deity

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    Are you poking fun at my technical drawing skills?!?

    Regardless of temperature improvements, since the factory VRAM thermal padding is defective, I still think the repadding helps at the extreme limits. After repadding, the VRAM chip will have proper cooling to the heatsink. Thus, the VRAM chip should be able to continuously work harder at max temps. So you get significantly more performance at that temperature range.

    The impact might be more significant as one throttling chip might knock all 4 VRAMs out, whilst fixing one VRAM's cooling could bring all 4 chips back to speed (but not quite sure how the GPU thermals address one excessively hot VRAM chip). . .
     
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