It's possible to produce Thunderbolt 3 monitor output with an add-in-card such as GC-ALPINE-RIDGE. I tested it with the AKiTiO Node Duo through its dual PCIe slots. What about single slot enclosure? The prerequisite is a second PCIe slot to power the AIC. Buying a second PCIe expansion enclosure is too expensive. I got a couple of $10 PCIe powered riser cards to test and it was a success.

System specs:

Late 2018 Mac mini – i5-8500B/UHD Graphics 630 iGPU/8GB RAM/256GB SSD

eGPU hardware:

Mantiz Venus + Radeon WX 9100 + .5m Thunderbolt 3 cable

HP Z27q 5K + Choetech Thunderbolt 3 to 2x DisplayPort adapter + PCIe powered riser card

Hardware pictures:

Installation steps:

The power supply of Mantiz Venus has a SATA power cable and a 4-pin Molex cable. I used these two cables to connect the PCIe powered riser card (through Molex plug and 6-pin power plug via SATA to PCIe adapter). It seems the riser card needs both 12V and 3.3V connectors plugged in. When I tried connecting only one of the two plugs the riser card didn't work.

I don't have a Thunderbolt 3 monitor so I used a Thundebolt 3 to dual DisplayPort adapter to verify. This mess of adapters and cables are fairly straight-forward. Two DisplayPort signals went from the WX 9100 eGPU to the AIC to produce Thunderbolt 3 monitor output. Then the Thunderbolt 3 adapter splits into two DisplayPorts for the HP Z27q monitor. It took a while for the monitor to initiate and come on using this method. I believe a native Thunderbolt 3 monitor such as LG UltraFine 5K wouldn't take as long.

The two PCIe powered riser cards I bought were PCE164P-N06 VER 008S and PCE164P-N08 VER 009S. Only the PCE164P-N08 VER 009S worked in this test. They both came from the same seller on Amazon and have good build quality. There's foam padding on the bottom of the card. It's small enough to be mounted inside the Mantiz Venus and most other eGPU enclosures.

Benchmarks:

I ran Unigine Valley and Heaven through the internal display and external monitor to check the performance difference.

Internal Display External Monitor

Comments:

If you need an eGPU with Thunderbolt 3 monitor output, the Blackmagic eGPU is not the only choice. The component cost is about $60 for the GC-ALPINE-RIDGE and PCIe powered riser adapter.