2020 Lenovo X1 Yoga Gen 5 [10th,4C,U] + GTX 1080 @ 32Gbps-TB3 (Razer Core X Chroma) + Win10  

System specs 

• ThinkPad X1 Yoga Gen 5, 20UBCTO1WW
  • 14.0" UHD (3840 x 2160) IPS, touchscreen with Dolby Vision™ HDR 400, AR/AS, 500 nits
  • 10th Generation Intel® Core™ i7-10510U Processor (1.80 GHz, up to 4.90 GHz with Turbo Boost, 4 Cores, 8 Threads, 8 MB Cache)
  • 16 GB LPDDR3 2133MHz
  • iGPU: Integrated Intel® UHD Graphics 8GB
  • Windows 10 Pro, 20H2 (OS Build 19042.685), x64
• Storage: Western Digital WD Blue SN550 NVMe M.2 2280 1TB PCI-Express 3.0 x4 3D NAND Internal Solid State Drive (SSD) WDS100T2B0C

eGPU hardware 

• Razer Core X Chroma (no changes from retail), using ~2' TB3 cable provided with it
• MSI GeForce GTX 1080 ARMOR 8G )C 256-Bit GDDR5X PCIe 3.0 x16

Hardware pictures 

 (see above)

• Pulled the Razer out from behind the monitor for the photo, but normally it's tucked back behind left monitor
• Left monitor: Dell U2713HM 1440x2560 60Hz
• Right monitor: Dell S2716DG 2560x1440 GSync
• USB keyboard is the UltimateHackingKeyboard, plugged into eGPU directly
• USB 5GbE Sabrent network adapter, plugged into eGPU directly
• Anker USB wireless mouse, plugged into eGPU directly
• Bluetooth Seinheisser Momentum 3 headphones

Installation steps 

• Unplugged laptop from prior docking solution, a Lenovo Workstation Dock Gen 2
• Inserted GTX 1080 into Chroma, hooked up power to card
• Plugged in all existing USB devices (+ USB hub) into Chroma
• Plugged in TB3 cable to laptop and turned on enclosure
• Windows diddled around for a bit and automatically installed some drivers. Rebooted once after this.
• Enabled Hardware-accelerated GPU scheduling in Windows settings. Rebooted.
• Further troubleshooting took place (to continue to take place) to iron out mouse stuttering/keypress repeating issues.*

Benchmarks 

Prior testing with the built-in Intel UHD Graphics and the Lenovo Workstation Dock Gen 2:

With the Razer Core X Chroma and the NVIDIA GTX 1080:

Comments

1. Previously, docking would take a while mostly as Window would refresh all the visible windows to scale them up/down from the laptop's own high-density LCD display. Now this redrawing process seems much faster possibly as the eGPU is now assisting.
2. Home Designer 2018 Pro (CAD-like architectural program) 3D views are considerably faster*
3. Destiny 2 runs on high graphics flawlessly*

*Mouse Troubleshooting

The first time I fired up Destiny 2 to play (note: KBM plugged into Chroma) I noticed the keyboard would cut out and so did the mouse. I plugged in an Xbox gamepad and the same thing occurred. I realized I hadn't reboot after having enabled "Hardware-accelerated GPU scheduling". After this things had improved so I could game in Destiny 2 with no problems.

However when I tested Home Designer's 3d view I still ran into something similar where the mouse would effectivelyjust stop working when the window was in focus. It's like when your mouse gets some hair underneath it or the batteries run out and it just stops working in spurts. However if I plug the mouse directly into the laptop then I can reliably use the mouse just fine in HD's 3d view-- however this is less than ideal as I want a single-cable docking solution. Further complicating things there are times where when the mouse is plugged into the eGPU and Home Designer's 3d view is just fine with the mouse.