Need help to find the ground loop path in this diagram
It means you have 2 ground connections, one in the PC and an other in the daq power plug, if the pc and the daq are spaced there may be a voltage difference between those grounding points and current may flow, that current can be high enough to the point of burning the cables, and in the case there ground wire between the pc and the daq breaks the voltage can destroy the usb ports for example, that is assuming the SMPS output is not isolated from ground or that the ground from the board is not connected to chassis, otherwise, then there is no ground loop