what is the EXP GDC slim line switch for?
title says it all, there is a switch on the mainboard of the exp gdc 8.4b named "slim line" with 2 options, "stand" the default one, and "ultra" couldn't find anywhere what they do, does anyone know?
Haven't found anything in the EXP GDC product documentation referring to the slim line jumper.
What we can find is egpu.io's wimpzilla required switching his EXP GDC 8.4d's slim line jumper from stand to ultra to ensure bootup and eGPU detection at: https://egpu.io/forums/builds/2011-15-dell-xps-15-l502x-r9-270-2gbmpci-e-x1-exp-gdc-v8-4d-amd-egpu-detection-and-internal-display-trick/
I played around with it quite a bit and it doesn't seem to do anything on my system. There are quite a few missing components on the PCB near the switch so I have a feeling it's something that's not fully implemented.
Further analysis on the pcb reveal why it help sometimes with performances and detection.
Slim line jumper control the USB port on the GDC, looking for the pcb traces, it seems that the ultra mode disable the USB. But to be honest i didn't plugged a single usb into it, so i didn't really checked, i went ultra and stayed in ultra, seems the final result is quite good. It would be nice, if you wanna try, to plug out a usb with normal/ultra!
Since i do not found on the hdmi/mpci-e cable pinout the USB DATA +/-, i can only suppose that is linked somehow to the pci-e lanes, if the usb work! Dunno how but it seems like that.
I finally meet the guy for the second hand but new multimeter and can further analyze the pinout and pcb.
Edit: When you switch to ultra, one USB DATA track is grounded, when normal, both USB DATA connect to the hdmi connector.