Reliability – PS_ON# Toggle for S0ix Mode (Required)

In order to optimize desktop platform power consumption, Intel provides design recommendation to enable power supply PS_​ON# toggle on/off during S0 idle power mode (S0ix) to save both system and PSU power. The power supplies’ PS_​ON# may toggle on/off periodically (for example, could be off for ~180s, then on for 1s, then off again). Desktop platform design implementation of S0 Idle Mode (S0ix) is different from the legacy S3 desktop platform design where PS_​ON# only toggle once when turn on, the S0ix desktop platform is expected to toggle PS_​ON# much more often. The S0ix mode is used in systems that support Alternative Low Power Modes.

In the example case where the computer turns off/on/off every 180 seconds, the worst-case scenario would be 480 times in one day and 175,200 times in one year. The power supply needs to be able to handle these many cycles for the life of the power supply.

To have better user’s experience, it is strongly recommended to avoid PSU fan acoustic noise annoyance, and relieve problems of mechanical fan failure, system and PSU designers may consider having at least two seconds delay time for the PSU fan to spin up after PS_​ON# assertion. PSU is expected to support running at full load without any electrical, thermal components (i.e. IC, MOSFET, diode, transformer, inductor, capacitor, relay, fan, etc.) damaged or degradations during the period of time before the warranty expired. Due to the frequent PS_​ON# toggle on/off, system and PSU component’s reliability should be considered based on the days, months, or years of claimed warranty listed on product specification. This is also mentioned in Section .