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.


Fixing Windows Store error 0x80073cf9 on Windows 8.1

So I was having a problem with the Windows Store on Windows 8.1. Apps couldn’t install or update, they would give the error 0x80073cf9. After having tried a few of the solutions online, none of which worked, I decided to see whether Microsoft could help. So I went to Microsoft’s site, and eventually arrived at the Answer Desk, where they offer chats with technicians. After a stupid mistake on my part when I accidentally closed the window on the first technician I was chatting with, I ended up reconnecting with Farah V. She was happy to help, and offered to remote into my computer to fix it. I consented, and watched as she typed commands, created folders, renamed folders, rebooted and so on. Below follows the commands she typed and actions she did that eventually fixed the error, in case anyone else is experiencing it.

PLEASE NOTE THAT A LOT OF THESE COMMANDS CAN BE DANGEROUS! ONLY RUN THEM IF YOU’VE TRIED EVERYTHING ELSE. All the standard disclaimers about not bearing responsibility if you break your own system of course apply.


Firstly, in an administrator command prompt, “sfc /scannow” claimed there was file corruption. Then, running the App Troubleshooter claimed that the graphics driver was not up to date. This proved to be a false lead.

She seemed to know where the file corruption might be present, so she navigated to C:\Windows and checked whether the folders “C:\Windows\AppReadiness” and “C:\Windows\AUInstallAgent” were there. One of them wasn’t, so she created it. She then further rebooted into safe mode and renamed “C:\Windows\SoftwareDistribution” to “C:\Windows\SoftwareDistribution.old”. She also renamed “C:\Windows\System32\catroot2” to “C:\Windows\System32\catroot2.old”. One of these folders was difficult to rename, so she had to stop some services to be able to rename them. And furthermore, this caused the programme signatures to go bad, so the publishers of programmes could no longer be verified. Scary. But this fixed itself a few hours later it seemed.

The final thing she did was to reboot again, and first in an administrator command prompt type “dism.exe /online /cleanup-image /restore-health”  and in an administrator Windows Powershell type “Get-AppXProvisionedPackage -online | Remove-AppXProvisionedPackage -online”. Finally, the apps in Windows Store would install, and she had fixed it. Well done Microsoft for knowing your way around your system, but this was honestly a bit too difficult a fix to do. I’ve typed out this post because I haven’t seen all these fixes listed on the web previously, and it might be useful to someone out there.

Anway, big thanks to Microsoft for having patient technicians employed like this. But somehow, I’d rather that they listed these commands somewhere so that one could run them one at a time to observe the effects.