V4 - Automatic 1x PCIe
Comment from xavier serra:
According to SPEC schematics page 13. To use 1x PCIe should be at 3V3 volts. I propose to connect R149 not directly to GND, but at pin b32 of J2 and mount R139 (values of resistors should be recalculated). In this way if there is no GND on b32 the GN4124 is automatically configured as 1x. In the same way it should generated automatic a short in connector J2 between pins b17 and a1 (for card detection).