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2018 15" Dell XPS 15 9570 (GTX1050Ti) [8th,6C,H] + GTX 1080 T[email protected] (ASUS ...
 

2018 15" Dell XPS 15 9570 (GTX1050Ti) [8th,6C,H] + GTX 1080 [email protected] (ASUS XG Station Pro) + Win10 1809 [itsage]  

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itsage
(@itsage)
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Joined: 3 years ago
 

Seeing numerous reports on lower-than-expected eGPU performance on 8th generation H-CPU hosts, @nando4 and I have been looking into the culprit. The Dell XPS 9570 in this build is one that experiences low performance during eGPU use. Nando tested a Dell Latitude 5591 and observed the same behavior. We discovered there's an oversight in cooling the PCH through which Thunderbolt 3 connection is attached on these laptops.

As seen in the photos above, the PCH chip of the XPS 9570 has no cooling. Dell had installed a thermal pad for the NVMe SSD on the other side and it draws heat onto the bottom case. I replicated this same cooling for the PCH with a 2mm-thick thermal pad square. The chipset sits lower than SSD and the added 2mm pad didn't quite reach the aluminum surface of the bottom case. A more permanent cooling solution is to use 3mm+ thermal pad with a wider contact surface.

 

System specs:

2018 15" Dell XPS 9570 - i7-8750H/GTX 1050 Ti Max-Q dGPU/UHD Graphics 630 iGPU/16GB RAM/256GB SSD

 

eGPU hardware:

ASUS XG Station Pro + ASUS Strix GTX 1080 Ti + 1.5m Thunderbolt 3 cable

 

Hardware pictures:

 

Installation steps:

Thunderbolt 3 Windows laptops are plug-and-play as long as Intel Thunderbolt Software is present. Once you approve the new Thunderbolt device (eGPU enclosure) all subsequent hot-plugs require no interaction. The drivers for Max-Q dGPU is slightly different than driver packages downloaded from Nvidia website. Therefore you should use the Nvidia drivers original to the laptop for both dGPU and eGPU. If you uninstall them and go with the latest drivers on Nvidia website, the Max-Q dGPU will require a reinstallation to function.

HWiNFO64 is one of the few software tools to monitor PCH temperature. With the stock no-cooling system of XPS 9570, the PCH would reach above 80 degrees Celsius within 10 minutes of eGPU use. This triggered thermal-throttling of the transfer rate through this chipset and eGPU performance suffers significantly. Once I applied the thermal pad, the PCH ran cooler and experienced less thermal-throttling. The performance with GTX 1080 Ti eGPU seemed more stable. Here are the before and after temps of PCH chipset.

 

Benchmarks:

Dell improved the Thunderbolt 3 connection of its 2018 XPS lineup with x4 PCIe lanes. We wish they had configured the XPS 15 to provide TB3-CPU attachment like Alienware laptops. That would skip the PCH entirely and yield the best performance possible for Thunderbolt 3 eGPU. Below are AIDA64 GPGPU screen captures for GTX 1050 Ti Max-Q dGPU and GTX 1080 Ti eGPU.

 

Here's the fluctuation in GTX 1080 Ti eGPU performance without cooling on PCH chipset.

No Cooling 2mm Thermal Pad
XPS 9570GTX 1050 Ti dGPUGTX 1080 Ti eGPU LoopbackGTX 1080 Ti eGPU External Monitor
Unigine Valley1,6734,2684,465
Unigine Heaven9082,2722,500
Unigine Superposition5,16314,81816,405
Tomb Raider 201362.3 FPS131.8 FPS159.4 FPS
Shadow of Mordor53.8 FPS92.8 FPS109.0 FPS
Dirt Rally62.5 FPS97.5 FPS108.5 FPS
Hitman59.6 FPS92.2 FPS96.3 FPS

 

Comments:

It's unfortunate Intel and PC vendors don't pay more attention to Thunderbolt 3 in general and eGPU use in specific. We hope our discovery of performance deficiencies would alert users and manufacturers to take actions. If you have these Intel H-CPU laptops and the performance have not been up to your expectation, open the back cover and let us know what you find.

This topic was modified 5 months ago

Best ultrabooks for eGPU use

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mac_editor
(@mac_editor)
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Joined: 2 years ago
 

That is a massive (~25%) difference is performance, with a single thermal pad. Impressive and super-beneficial that you found a rather simple/cheap fix for this.

purge-wrangler.shpurge-nvda.shset-eGPU.shautomate-eGPU EFI Installer
----
Troubleshooting eGPUs on macOS
Command Line Swiss Knife
eGPU Hardware Chart
Multiple Build Guides
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Current: MacBook Pro RP560X + 480/R9 Fury/Vega 64 | GTX 780/1070
Previous: 2014 MacBook Pro 750M + 480/R9 Fury | GTX 780/980 Ti/1070


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nando4
(@nando4)
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Joined: 3 years ago
 

The lack of any PCH cooling on a sample of H-CPU Dell 8th generation notebooks resulting in them throttling above 80 degrees  is a significant finding. Not only does this result in inconsistent eGPU benchmark results it affects NVME SSD benchmarking as well.

NOTE:  U-CPU notebooks have the PCH on the CPU so is cooled as part of the CPU heatsink. These systems are not affected.

Ultrabook News noticed the disparity between U and H XPS performance here , quoted below.  Though we now know the culprit for this is a throttled H-CPU PCH chip.

My benchmarks done on my Mantiz Venus + GTX 1070 setup seem to confirm this, though I have noticed that the graphics performance is significantly better with my XPS 13 9370 versus my 9570.

Despite a physics score of over 14,000 (compared to the ~9500 the 9370’s i7-8550U achieves), a lower graphics score brings the total score down significantly. I am not sure if this is driver or BIOS-related, but my current theory is that where the XPS 13 9370’s TB3 signal feeds directly to the CPU, the XPS 15 9570 is using an additional daughterboard (Alpine Ridge) to provide TB3, which may induce some performance degradation in comparison.

This post was modified 5 months ago

eGPU Setup 1.35    •    eGPU Port Bandwidth Reference Table    •    Several builds
2015 15" Dell Precision 7510 M1000M + GTX 1080 Ti @ 32Gbps-M2 (ADT-Link R43SG) + Win10


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OliverB
(@oliverb)
Noble Member
Joined: 9 months ago
 
Posted by: nando4

The lack of any cooling on a sample of H-CPU Dell 8th generation notebooks resulting in them throttling above 80 degrees  is a significant finding. Not only does this result in inconsistent eGPU benchmark results it affects NVME SSD benchmarking as well.

NVMe SSD benchmarking is an important thing. If you ask for an external SSD in a shop, you will only get SATA. They don't even have external NVMe SSDs. This is pathetic. SSD can do so much more. It's not just numbers, it's much faster, very notable.

SSD NVMe disc benchmarks
SSD NVme disc benchmaks 2

This post was modified 6 months ago

2018 15" MBP & 2015 13" MBP connected to RTX2080Ti GTX1080Ti GTX1080 Vega56 RX580 R9-290 GTX680


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itsage
(@itsage)
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Joined: 3 years ago
 
Posted by: nando4

The lack of any PCH cooling on a sample of H-CPU Dell 8th generation notebooks resulting in them throttling above 80 degrees  is a significant finding. Not only does this result in inconsistent eGPU benchmark results it affects NVME SSD benchmarking as well.

NOTE:  U-CPU notebooks have the PCH on the CPU so is cooled as part of the CPU heatsink. These systems are not affected.

Ultrabook News noticed the disparity between U and H XPS performance here , quoted below.  Though we now know the culprit for this is a throttled H-CPU PCH chip.

My benchmarks done on my Mantiz Venus + GTX 1070 setup seem to confirm this, though I have noticed that the graphics performance is significantly better with my XPS 13 9370 versus my 9570.

Despite a physics score of over 14,000 (compared to the ~9500 the 9370’s i7-8550U achieves), a lower graphics score brings the total score down significantly. I am not sure if this is driver or BIOS-related, but my current theory is that where the XPS 13 9370’s TB3 signal feeds directly to the CPU, the XPS 15 9570 is using an additional daughterboard (Alpine Ridge) to provide TB3, which may induce some performance degradation in comparison.

Thank you for your analysis. Both XPS 9370 and 9570 have the same Thunderbolt 3 <-> PCH <-> CPU. The only difference we found is the PCH in XPS 9370 gets proper cooling while XPS 9570 has nothing. Here's a view of the XPS 13 9370 motherboard. Even the Thunderbolt 3 controller and USB-C controller have a heat shield.

In contrast, Dell H-CPU laptops have no PCH cooling at all. Razer Blade 15 is one of the few we found with PCH cooling.

Dell Latitude 5491 Dell XPS 9570 Razer Blade 15
This post was modified 5 months ago

Best ultrabooks for eGPU use

eGPU enclosure buying guide

109 external GPU build guides


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RimsOnAToaster
(@rimsonatoaster)
Eminent Member
Joined: 2 years ago
 

Woah that's massive! I'm thinking of revising my build log again to make this point known. What should I do pre-thermal-pad and post-thermal-pad to demonstrate the difference in performance?

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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itsage
(@itsage)
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Joined: 3 years ago
 

@rimsonatoaster I recall your XPS 9570 is iGPU only so the cooling system may be slightly different. The PCH chip location and its lack of cooling should be the same though. My process to reproduce and document the PCH overheating during eGPU use was to run HWiNFO64 in the background to monitor temp and perform tasks that stress the PCH. As @nando4 mentioned NVMe SSD traffic goes through this chipset as well. When you see the temperature gets above 70 degrees Celsius, you can run Fire Strike stress test for example.

The 2mm thermal pad I used was not ideal but helped tremnedously. If you can find 3mm or thicker, try those out. The best scenario is to have the thermal pad make contact with both PCH chip and aluminum back cover of the XPS. I'm looking forward to seeing your experience.

Best ultrabooks for eGPU use

eGPU enclosure buying guide

109 external GPU build guides


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PureLife
(@purelife)
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Joined: 7 months ago
 

That is very well researched, thank you itsage! Out of curiosity do you know which laptops have proper cooling for the PCH chip? I'm eyeing the Lenovo X1E but not sure if anyone has checked that one out yet.

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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itsage
(@itsage)
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@purelife The Lenovo X1 Extreme doesn't have cooling on its PCH chip. You can see this featured photo of its cooling system right on the product page. No PCH cooling is very common on 8th gen H-CPU laptops from what I've seen unfortunately. 

This post was modified 5 months ago

Best ultrabooks for eGPU use

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PureLife
(@purelife)
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Joined: 7 months ago
 

That's unfortunate indeed! So I guess we have 2 options now: buy a Razer Blade or DIY our thermal solution on other 8th gen H-CPU laptops.

I can't believe this issue doesn't trigger any Quality Control review in any manufacturer. It makes me wonder if it's Intel who tells their vendors that eGPU usage is an unusual use case and thus the PCH chip does not need cooling.

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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itsage
(@itsage)
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Joined: 3 years ago
 

Most vendors consider Thunderbolt 3 eGPU as a Mac thing. Therefore they are hesitant to add Thunderbolt 3 connectivity and when they do it's usually poorly implemented.

Best ultrabooks for eGPU use

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109 external GPU build guides


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realbronz
(@realbronz)
New Member
Joined: 4 months ago
 

Just wanted to leave my results here, will provide screen caps upon request: 

So I stacked three 1.5mm thermal pads squares on top of the PCH component. I was basically trying to match the height of the SSD + Thermal pad height so that the heat can be dissipated onto the bottom of the chassis. 

Temps went from 81 degrees Celcius to 69 degrees Celcius on average and I got a boost in performance as well.

I just ordered some 3mm thick thermal pads on Amazon and will try those to see if I can get better results. Since, ~4.5mm is the height between the PCH and the chassis, I might have to add one more 1.5mm pad as well.

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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