This counter records how many I2C bus communication errors occurred between the chassis management controller and a blade's power supply unit during the archived interval covered by this historical row. I2C is the low-speed management bus the PSU uses to report its own telemetry (voltage, current, temperature) back to UCS, so a rising count here points to a flaky backplane connector or a failing PSU controller rather than an actual power-delivery problem. For instance, seeing PsuI2CErrors jump from 0 to 40 in one interval on a single PSU, while its sibling PSU stays at 0, is a strong hint that specific unit needs reseating or replacement.