32 Posts
0
4872
XPS 15 9570 "Ambient Sensor" goes up to 125°C under load
There is no thermal throttling or something, but HWiNFO64 reports Dell's EC Ambient Sensor with around 100 to 125°C while under load (idle around 45°C) and stays at this temp.
While the GPU is stable around 76°C and the CPU at around 65°C, this high ambient thermals are not expected. Also, the machine is still a couple of watts under its power limit. Is this expected or may it harm the machine? Screenshot attached:
samos1111
489 Posts
0
July 24th, 2018 02:00
Stacked heat pads are generally not the best idea because their thermal conductivity is not so good. But if padding the VRMs to the backplate, good conductivity is actually a problem, because then (in the absence of an external laptop cooler with fans) the backplate heats up too much, then the intake cooling air heats up, and things get actually worse in the long run. Even good quality pads >10 W/mK made things worse.
The alternative approach with the pad sheet bridge uses the pad in an even more unorthodox way. In other laptop designs, such bridges for VRMs are implemented with metal conductors or even heatpipes. But there is not much space to play, and the complication increases because with metal you must take care of proper insulation and fixing to avoid shorts if sth moves. You can also consider redirecting some cooling air as in iunlock's mod.
Iunlock's mod uses cheaper mini heatsinks that don't need to be cut. And doesn't mate them via the pad to the baseplate, but to an internal copper sheet instead which is airgapped to the baseplate. The copper sheet is cut from the one beneath the black insulation foil on the inside of the backplate, but one can get another one so that the backplate remains intact.
Another trick is to use electrical insulation tape to seal the gap between the heatpipe and the case edge so that more air is forced through the cooling fins, on both sides.
And another to raise the rear of the laptop from the desk with a ca 2cm thick bar (almost as good as a laptop cooler pad). Or place the laptop in a freezer, or at least on air conditioner duct opening ;)
pep0sn
32 Posts
0
July 23rd, 2018 08:00
Oh, I found out that these seem to be the VRMs. Is this temperature normal under heavy load?
samos1111
489 Posts
1
July 23rd, 2018 14:00
I don't think so. And the mosfets tend to be even hotter than the sensor. Maybe this is why some are getting freezing/restarting under load. In the previous models, PL1 throttling started when this sensor was around seventies. The 9570 seems to throttle when DIMM hits 63.
I guess Dell will "fix" this with a BIOS and/or Intel DPTF update. But you won't like the effect (throttling).
I suggest you to use thermal pads to cool the VRM mosfets. It is relatively easy, reversible, any unlikely to break something (nonconductive). Most commonly a few layers of Arctic 6 W/mK are stacked to about 5mm to fill the gap between the mosfets to the backplate; but the backplate can't dissipate much heat. A more recent idea is to use a larger pad sheet to bridge the mosfets with the heatpipe not touching the backplate (you may have to convince the pad to stay in place somehow if it isn't sticky enough).
If you get throttling due to DIMM at 63, try padding the RAMs and their sensor in between to the backplate (assuming you have not padded the VRMs to the backplate).
Look up instructions at Dell reddit and at Notebookreview XPS forum. There you can also check iunlock's mod, where the idea is to add internal cooling surface for the VRMs and redirect a bit of the cooling air from the vents over there, so that it takes VRM hear out via the central grille (mind zero air movement over this hot area by default).
pep0sn
32 Posts
0
July 23rd, 2018 16:00
Hi samos,
thanks for your response! I agree that this temperature can't be healthy for none of the parts. I saw the iunlock guide - I must confess that I'm not a huge fan of using a lot of stacked heat pads. I ordered a few of these mosfet sinks: https://www.amazon.de/dp/B004CLDIHK/ref=pe_3044161_189395811_TE_SCE_dp_1 (Enzotech) and will attach them with some sticky cooling pads in between. The "spikes" of the cooler can be shortened to fit under the backplate. I will try it with and withouth attaching a cooling pad on top (to connect it to the backplate or the heatpipe).
I will report back my learnings from that!
pep0sn
32 Posts
0
July 24th, 2018 04:00
Thanks samos, I'll have a look at the different solutions and report back!