A list of pinouts. Pin 17 is listed as "VCC SUS" https://digipres.club/system/media_attachments/files/113/047/810/805/546/787/original/e9f2dd0985053b40.png
apparently instead of having a "POWER GOOD" pin like ATX PSUs do, they went for the opposite, where they have a pin that tells you if the power is sus *amongus noise*