Half-height miniPCIe to standard PCIe x1 interface board, expandable with discrete graphics card

Using a half-height miniPCIe form factor, it features one PCIe x1, one USB 2.0, and one SMBUS port. The PCIe x1 port connects to a USB 3.0 female connector, while the USB 2.0 and SMBUS ports are reserved pads. The PCIe x1 pinout is compatible with various mining cables on the market. A standard PCIe x16 expansion card, such as a discrete graphics card, can be connected via a USB 3.0 male-to-male cable, but the bandwidth is limited to x1.
 
 
In actual testing on an industrial control board with the J1800, a mining cable was connected, and a 16GB Optane M.2 SSD was successfully recognized via a PCIe x16 adapter.
 
 
Actual test results, as shown in the image, show a read speed of 290MB/s and a write speed of 150MB/s, with no speed drops or errors during full disk read/write operations. The J1800 theoretically supports a PCIe 2.0 x1 bandwidth of 500MB/s, so the speed not being fully utilized is likely due to the J1800's limited performance.
If the platform is relatively new, such as J6412 or N5105, the interface supports PCIe 3.0 x1, doubling the bandwidth to 1GB/s, resulting in a significant speed improvement.
Theoretically, a dedicated graphics card can be used, but I don't currently have one without independent power supply, so I can't test it. I may add test results for a dedicated graphics card later.
The PCB has impedance matching and differential length equalization. For board fabrication, please choose the JLC7628 layer stack-up specification, 1mm board thickness; free prototyping is supported. Immersion gold plating is recommended, as the gold fingers have better reliability.