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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    Gerty,

    You can see in HWINFO64 some extreme benchtesting on an i7 in R#ph's post quoted below.

    As you might guess, running Prime95, his repaste drops CPU temps but does not really drop Ambient sensor #1 temps (pictures 1 &2)

    Surprisingly, when he runs very extreme benchmarks, CPU temps fall with the repaste but Ambient sensor #1 skyrocketed to 114*C (pictures 3&4)! Caution as those temps can shorten lifespan of many electronic bits. Part of that temp spike could be a sensor that is not too accurate at extremes, or because his repaste work included using the bottom cover as a cooler via thermal pads to the heat pipes (and the cover got really hot causing as gonZ0 called a something like a thermal feedback loop where hot air was being pulled in by the fans). Or the system just going out of control at extreme limits.

    For your reference, today I ran my i5 6300HQ with RealBench 2.44 stress test for 15 minutes in a (very) hot room (30*C), HWiNFO64 shows the following max values (FYI CPU and GPU were repasted, VRAM thermal pads were replaced, no undervolt)

    Room (est) 30
    CPU: 83
    Ambient: 78
    Ambient: 76
    Temp3: 48
    Ambient: 61
    Ambient: 63
    Ambient: 56
    DIMM: 66
    NVIDIA 88
    PL1 min 15.375
    CPU min 1.1GHz
    CPU-fan ~5000RPM
    GPU-fan ~5000RPM

    In a cool room (~22*C) with undervolt, the results are much better as you can see in a prior post. Undervolt makes no real difference today in this hot room

    I think you could download trial Aida64 to cross reference exactly what these ambient sensors are; I think #1 is the H56 located in the voltage regulator area.




     
  2. Brian Anderson

    Brian Anderson Newbie

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    Yes, I just grabbed a small USB powered fan and sat it between the F7/F8 keys and the Dell logo pointed down.
    Here is a graph of the temp difference:
    [​IMG]
    Unlike my old board, the VRM temp roughly tracks my GPU temp even without the forced cooling which is acceptable to me, but I wanted to post this to illustrate the difference.

    The audio problem is one that either (randomly) causes no sound or a BSOD. After a lot of reading I think it was caused by my lappy going thermonuclear when Windoze Update decided to wake it from sleep in my backpack. When I found it two hours later it was so hot I couldn't touch it - 95% of the battery discharged in a backpack in a notebook sleeve. Shortly after that I started having the audio issues described here. The only fix, after many many tests and confirmed by others, was to have Dell replace the hardware.
     
    Last edited: Sep 5, 2016
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  3. pressing

    pressing Notebook Deity

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    Thanks for the detailed response Brian. Glad that USB fan idea helped thermals. Hope I don't end up with that cooked motherboard as a refurb from Dell "service"!

    Some quick thoughts:

    - A few guys here noticed thermal improvements just lifting the laptop into the air (like 5*C)

    - GonZ0 also noted the long rubber feet in the back and front are cleverly designed barriers so the fans intake air from the sides, rather than suck hot exhaust from the back

    So a few simple ideas I had:

    - Passive cooling - Could improve general thermals just by building 2 long solid feet (25cm x 1cm x 0.2cm) say with concave tops to accommodate the 9550s rubber feet. That would allow more airflow into the fans and maintain some of the barrier system. Maybe connect the solid feet with a collapsible X structure for strength and portability

    - Active cooling - I like something like the cooler master U2 plus because you can shift the fan position easily. I don't like the bulky feet much, however. But it might work better adding a DIY barrier system

    - With the active cooling pad above, it could make sense to buy a used 9550 bottom cover and poke some holes for fans to directly cool the voltage regulators. I think (but am not sure) the voltage regulators are just below the middle grill section that Dell covered with some mylar/copper which would be easy to puncture. As a used bottom cover is $20, that is not an expensive experiment. It is a pretty "brute" solution as the air into the voltage regulators has no real place to easily go but a rough exhaust pipe could be built I suppose for some balance.
     
    Last edited: Sep 5, 2016
  4. custom90gt

    custom90gt Doc Mod Super Moderator

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    So just for S&Gs I decided to throw thermal pads on the R22-604-111s and sink them to the case.

    I ran 2 (yes only two) loops of 3dmark time spy before the thermal pads and had a max VRM temp of 79*C.

    After that I tried with thermal pads with two more loops of 3dmark time spy and my max VRM temp was 67*C.

    When I have more time to mess with it I will update this thread.
     
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  5. GoNz0

    GoNz0 Notebook Prophet

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    Only issue I found when using the case as a heatsink is eventually the case heats up in turn heating the incoming air causing an increase in temps until the entire laptop heats up then it can't cool and well you can probably guess the rest :)
     
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  6. pressing

    pressing Notebook Deity

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    Interesting option!

    I saw several people here earlier this year used the bottom case as a heatsink by connecting the CPU/GPU heatpipes via thermal pads. I think everyone removed them. GonZ0 noted the intake air got heated and caused a bad thermal loop. Some also complained the bottom / top got too hot to touch.

    But the VRM produces little heat and needs little cooling so maybe this is a good option. What thickness pads did you use? Which pads did you use? Unfortunately, those pads get quite useless as they get thicker...
     
  7. custom90gt

    custom90gt Doc Mod Super Moderator

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    Right, I wasn't a fan of cooling the heatpipes from the cpu/gpu due to that issue, however I don't know how much energy is being dissipated by the R22s and the case in comparison. I would have to spend a lot more time than I have to figure if the juice is worth the squeeze, but I'm trying to throw out ideas for the people having throttling issues.
     
  8. GoNz0

    GoNz0 Notebook Prophet

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    Let it run daily stuff, surfing the net and very little load, the sort that spins the fans on low now and again. That is all I did with the pads from heatpipe to case and after an hour the palmrest heated up and the bottom was about 40 degrees causing the thermal loop and fans spinning up to 3000 until I gave up.

    Would be great if the VRM's (is that the R22's as I was browsing on my phone the past week on holiday so I haven't really kept up to date due to alcohol abuse!) didn't cause a thermal loop!
     
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  9. custom90gt

    custom90gt Doc Mod Super Moderator

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    Yeah I'm trying to run loops of 3dmark while I study on the desktop to see if it gets heatsoaked...

    I used 1mm thick just cheap silicon thermal pads. They aren't the greatest, but if they can knock 10*C or so off it may be worth it.
     
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  10. custom90gt

    custom90gt Doc Mod Super Moderator

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    Yeah I'll leave them on for a week while at school and what not to see how it does. Any increase in fan noise or palmrest temps will be pretty easy to notice since I typically use the laptop 8+ hours a day.
     
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