Six-way comparison of my eGPU setup

I like thin and light notebooks. But I also like having the graphics horsepower available when at my desk to play the occasional game. In the last few months, external GPUs connected by Thunderbolt 3 are starting to appear, and I was lucky enough to get my hands on a PowerColor Devil Box. And unlucky enough to experience an initial incompatibility between the Devil Box and my laptop, a recent Kaby Lake Dell XPS 13 (9360).

Luckily though, I have received a firmware update for the Devil Box, which allows compatibility with my laptop, so I thought I would finally do some testing of the setup.


Laptop: Dell XPS 13 9360
CPU: i7-7500U
internal GPU: Intel HD graphics 620

eGPU enclosure: PowerColor Devil Box
eGPU: Sapphire AMD Radeon RX470 4GB

Now, I use Arch Linux as my daily driver, and I’m pleased to report that the eGPU is detected, and can be used to render any application by simply setting the environment variable DRI_PRIME=1 (when using Wayland). The only issue I’ve had with Linux is that the system doesn’t really like when unplugging the eGPU while running, so I have to turn the laptop off before unplugging. I might investigate this some other day, but it is no big deal, since the eGPU can be connected while the computer is running with no issues.

Anyway, on to the benchmarks. I am running Unigine Heaven on Extreme settings, and rendering on the laptops internal screen:

Quality:       Ultra
Tesselation:   Extreme
Anti-aliasing: x8
Fullscreen:    no
Resolution:    1600x900

The scores were:

OS          (API)      eGPU   iGPU
Windows 10  (DX11)     1322    211
Windows 10  (OpenGL)   1230    199
Arch Linux  (OpenGL)    816    146

So what can we gather from this? Firstly, Linux OpenGL drivers are not as good as Windows OpenGL drivers. Secondly, DirectX 11 performs better than OpenGL. Finally, an eGPU is a compelling upgrade in my case.

So what’s left? Well, I’ve ordered a replacement fan for the front of the Devil Box. I was so tired of the constant high-RPM spinning, that I have unplugged both fans. But this leads to the PSU fan spinning up when under load, and the little fan on the PSU is very loud (although with quite a pleasant smooth sound). I hope a lower RPM and better fan in the front of the Devil Box will prevent this. Also, I need to investigate ways of improving the Linux experience: fix the problems when unplugging, and work out how to change the fan profile of the card when running in Linux.

Author: jpamills


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