Following the discovery of an 18bit-DAC which fails its autocal in x1susex, I moved the card within the chassis to see if the DAC autical failure follows the card. It does.

On inspection, this 18bit DAC differs from the other 4 in the chassis in that the S/N label on the solder side is smaller and placed closer to the front of the card. When we next open the h1susb123 and h1sush56 IO Chassis, we should check if those cards are visually different as well.