US$200 Chinese Domestic Market Thunderbolt 3 eGPU
@itsage, After Googling some obscure model numbers printed on the PCB, I found this very interesting article which includes what you suggested, plugging PCIe peripherals into the Thunderbolt card. Very interesting.
It also includes an image of the Thunderbolt chip, listed as an Intel DSL6340 Thunderbolt 3 Controller.
I have done preliminary testing with it and so far the results have been very promising.
- The eGPU works being hot plugged, cold plugged and can display BIOS and login screen (something my Gaming Box 1080 didn't do).
- H2D speed is good and benchmark performance is excellent.
- It does not provide any power to the host device.
- The power implementation is interesting. The Thunderbolt Controller and its associated PCB is powered only by the host device and doesn't seem to interact with the PSU at all. The red button on the eGPU PCB is a toggle on/off switch for the eGPU power. If you turn on your laptop while it is plugged into the eGPU but have the eGPU power switch turned off, and subsequently turn the eGPU power switch on AFTER the host system has posted, it will not be able to run the eGPU. A system restart fixes this.
- There is a 4 pin header and included 2 pin-bridge that is labelled 'power'. If you bridge the first two pins, it overrides the red switch and powers the eGPU. This is excellent for a custom case! Extending the power switch is as simple as a two-pin cable and switch.
- There are also unpinned connectors on the PCB labelled 'fan' that have traces to a small chip. I will have to test these with a multi-metre to see if they are providing power and if they could be used.
I ordered basically the cheapest fully modular PSU I could for the testing of the device, which I am currently regretting. The Silverstone ST55F-PB I have running it isn't powerful enough to run my Gigabyte 3060 Ti Gaming OC Pro. Each now and then during Timespy the GPU and PSU will shut down, leaving only the BUS powered Thunderbolt Chip running. I believe it is a PSU-power related issue for two reasons: Firstly I can run the GTX 1080 from my Gaming Box in it without any issue. And secondly, after reducing the 3060 Ti's power limit to 80% it seems to have stabilised. A more powerful (and maybe higher quality) PSU is in order.
@boltoway, Thank you for the thorough testing and detailed report. The Thunderbolt 3 mainboard was built as a bus-powered TBT device and therefore draws Power Delivery from the host. It's nicer this way when you want to use this board for other uses that require less than 15W PD. Really cool to see there are customization options with eGPU power-on and fans. Looking forward to seeing more from you on this build.