Correct positioning of VRM thermal pads in XPS 9570

Discussion in 'Dell XPS and Studio XPS' started by Mulgul, Jan 9, 2019.

  1. Mulgul

    Mulgul Notebook Enthusiast

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    Hey guys,
    I am new here, so forgive me if I get anything wrong. There has been a lot of discussion about the XPS 15 VRM temperatures. However, for the XPS 9570, I haven't seen any pictures yet on where to place the thermal pads to connect the VRMs to the back plate (to be used in conjunction with an external cooling pad). The question is not trivial, since the VRM placement in the 9550 and 9560 (for which suggestions exist) is different than in the 9570 (for which so far I have not found any suggestions on where to put the pads / where the VRMs are). So if this is my XPS 9570 motherboard:
    https://www.dropbox.com/s/7pu7lt66bu4fav6/20190109_231401.jpg

    Then this is where I would put the thermal pads:
    https://www.dropbox.com/s/vohur2y5rdowvoz/20190109_233426.jpg

    Would that be correct?


    Cheers and thanks!
     
  2. _sem_

    _sem_ Notebook Deity

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    Hum, "correct"? I think it would be correct if Dell mated the VRM mosfets with a heatpipe to cooling fins. This pads are just ad-hoc patches that don't really work well but are presumably better than nothing*.

    I haven't seen FLIR images or heatgun measurements for the open 9570 under load to tell which mosfets need to be padded most, but I guess you have left out a few. I assume you intended to leave some room for airflow, but mind there really isn't any, unless you divert some cooling air from the fins (check iunlock's mod).

    Also some report that power limit throttling in the 9570 kicks in when the DIMM sensor reaches 63 (may depend on BIOS and DPTF versions... check using HWinfo64). If this is so, the VRM mosfets may be better "bridged" with a pad sheet to the heatpipes without touching the backplate, and you may consider padding RAM (incl DIMM sensor) to the backplate to offset throttling by a few degrees. This is still a cheap and simple surgery

    *It appears that high-thermal-conductivity pads may be worse than nothing, because in the absence of a cooling pad the backplate may in the long run overheat and the hotter input air no longer cools the CPU and GPU well.
     
  3. Mulgul

    Mulgul Notebook Enthusiast

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    Hey,
    thank you for this!

    I am sure we can all agree that a better build would have been preferable. But in the absence of DELL doing its job, I guess we have to do with what we got. I also assume that we are all speaking about this solution in conjunction with an external cooling pad (it definitely makes no sense to just heat up the backplate). Now, I would consider myself as a technical intermediate, so putting pads on VRMs is fine with me, but bridging the VRMs to the heatpipe seems a bit too advanced for me. So if we stick around with the VRM-padding-to-backplate-plus-external-cooling-pad solution.

    Then my stupid question no 1 would be: VRM = MOSFET? Then: what else would have to be padded? Anyone got any ideas?

    I will also check for the DIMM sensor. But stupid question no 2: If I am padding the DIMM sensor itself, will that not be a problem, since I only prevent the heat from getting to the sensor, rather than letting it dissipate (to the backplate)? This would mean that I prevent the computer from recognizing that it actually does get too hot (so that it SHOULD throttle), rather than prevent the reason for the throttling itself (the heat buildup). Or would that not be a problem because the threshold of 63 is simply too low?

    That being said, I am actually not that unhappy, I can play Battlefield 5 on 1920*1080 with low/medium settings and while there is power limit throttling, the computer manages to stay above 2,2 Ghz, so the game is still absolutely playable. Maybe this is the limit of the GTX 1050 ti anyways?
     
  4. _sem_

    _sem_ Notebook Deity

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    > in conjunction with an external cooling pad (it definitely makes no sense to just heat up the backplate).

    On the 9550 & 9560, throttling from the first Ambient sensor near the VRMs, just shifting a little bit of heat to the backplate helps a lot, even if you don't even lift the rear of the laptop. An external cooling pad isn't essential; does help but not tremendously.

    > putting pads on VRMs is fine with me, but bridging the VRMs to the heatpipe seems a bit too advanced for me

    The other option isn't much more involved, folks seem to just get the Arctic 5x5cm pad (1mm?), cut it a little bit and slap on (not 100% sure if it sticks well enough). Light years from iunlock's thing.

    > VRM = MOSFET?

    I recall VRM probably stands for voltage regulator mosfet or module? Anyway the mosfets, thin black slices, are their power switching components that seem to produce most heat.

    > If I am padding the DIMM sensor itself, will that not be a problem, since I only prevent the heat from getting to the sensor...

    Best leave it alone before you are sure that temperatures are better because of VRM padding and you are sure that it triggers unnecessary throttling.
    The idea is to cool down this location by few degrees by padding to the presumably cooler case (if you also pad VRMs to it it may well get warmer not cooler). It would still throttle if overheated, just later.
    It is possible to kill throttling by removing Intel DPTF, but I wouldn't recommend it.

    > while there is power limit throttling, the computer manages to stay above 2,2 Ghz, so the game is still absolutely playable. Maybe this is the limit of the GTX 1050 ti anyways?

    Many gamers are okay if the CPU gets throttled but the GPU runs relatively free.
    Have you undervolted both (Throttlestop and MSI Afterburner), repasted (if there is direct throttling)?
     
  5. custom90gt

    custom90gt Doc Mod Super Moderator

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  6. Mulgul

    Mulgul Notebook Enthusiast

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    Hey custom90gt,
    this is exactly what I (and I think many others) have been looking for. However, it is also interesting to note that, if you have a look at my photos, my motherboard - including the placement of the VRMs apparently looks different than yours (even though we both own an XPS 9570). Weird, you would think that Dell uses the same motherboard for all XPS 9570s. I have the i9, maybe that explains the difference?

    And for _sem_ (also so that everyone else can get it): Your preferred solution would then be to just cut out a thermal pad that touches all VRMs and then either the backplate or the heatpipe?

    As a side note: thanks for this awesome help and I will try undervolting the GPU tonight, regardless from anything else.
     
  7. custom90gt

    custom90gt Doc Mod Super Moderator

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    Ah I didn't look at your picture. You have the newer revision motherboard with extra VRMs. Based on the one person on Reddit that had the same board, you likely won't have to sink the VRM at all (just a guess on my part based on his scores). Sadly without a lot of testing, I am not sure what the best advice would be for you. My hope is with the redesign and change to the VRM, temps will be lower VRM wise.
     
  8. Mulgul

    Mulgul Notebook Enthusiast

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    Different from what one might hope, I suppose the padding of the VRMs still seems necessary, as the newer version does not appear to be that much cooler. I can say this because I happened to have had an earlier version of the computer (also with i9) and I sent it back because of crashes and high temperatures. I have then reordered the computer for a second try (same configuration, but apparently revamped board).

    On the old motherboard (unevised board, same config) "temp 1" in hwinfo (I think this is the VRM sensor) went up to about 125 degrees Celsius when simultaneous stressing the GPU and CPU. After padding the VRMs, they were comfortably in the 90s. I then sent the computer back for various, unrelated reasons however.

    I then got my new XPS 9570 (which I am using now): Without padding, it stayed below 120 degrees, but not by much. So an advantage over the old configuration, but by only 5-10 degrees. Now with the pads applied as shown, it did not go above 88 degrees (but some power throttling occured nonetheless). So it seems the new VRMs are a bit cooler, but not by much.

    By the way, for all my XPS VRM temperatures never went through the roof as they did UNLESS the computer was a couple of centimeters above the ground. Just placing the computer on a hard surface meant GPU and CPU would get hotter, but not the VRMs. So if I used a cooling pad, the CPU and GPU would stay relatively cool, but the VRMs would get super hot. With the current padding, everything seems fine now (power throttling still occurs, but maybe unavoidable, right)?

    Stupid question no 3: Is it a problem if I pad some but not all VRMs as I might have done?
     
  9. custom90gt

    custom90gt Doc Mod Super Moderator

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    Yeah padding those are totally fine, you can always play with which ones to pad and see if that makes a difference. Sad that the new revision doesn't really help much.

    The power limit throttling is set by Dell but if you're comfortable with it, you may be able to remove the limit with throttlestop:
    http://forum.notebookreview.com/thr...ongfang-gk5cn6z.815943/page-274#post-10843849

    Just watch those temps. With the increased power limits comes hotter cpu and VRM temps...
     
    Dannemand and Papusan like this.
  10. _sem_

    _sem_ Notebook Deity

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    > Stupid question no 3: Is it a problem if I pad some but not all VRMs as I might have done?

    As already written, this is difficult to tell without measuring temperatures of the insides of the open laptop under full load with a FLIR camera or by moving a beam thermometer over individual components, opposed to the few measurements in this area available online (1st Ambient, DIMM... not sure if any other is near). Considering that we don't know which VRM feeds what, at what power...
    I recall such measurements for the 9560 are on a pic in the iunlock's thread http://forum.notebookreview.com/thr...ures-benchmarks-xps-15-9560-kaby-lake.802345/
    Mind there are two issues here:
    1st, to fix local overheating of the mosfets and their immediate surroundings
    2nd, to actually get the heat accumulating during prolonged heavy loads from the VRM area out of the laptop.
    The backplate padding approaches mainly address the 1st, while the 2nd only to a low degree, because the backplate can't dissipate much heat, even with a cooler stand. The bridge padding variant might do this better, but not sure if the pad can conduct much heat side-wise, and the CPU+GPU temps might rise a couple of degrees (perhaps not good with the GPU limit lowered to 74).
    The iunlock approach tackles 2nd too, by creating more internal "fin surface" and redirecting some of the cooling air from the fans over there and then out via the narrow central grille. But it is much more involved.
     
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