Power Supply Unit; Hot Spare Feature; Removing A Power Supply Unit Blank - Dell EMC PowerEdge R940 Installation And Service Manual

Figure 92. Installing optional IDSDM module
Next steps
1. Install the MicroSD cards.
NOTE: Reinstall the MicroSD cards into the same slots based on the labels you had marked on the cards during removal.
2. Follow the procedure listed in

Power supply unit

Hot spare feature

Your system supports the hot spare feature that significantly reduces the power overhead associated with power supply unit
(PSU) redundancy.
When the hot spare feature is enabled, one of the redundant PSUs is switched to the sleep state. The active PSU supports 100
percent of the system load, thus operating at higher efficiency. The PSU in the sleep state monitors output voltage of the active
PSU. If the output voltage of the active PSU drops, the PSU in the sleep state returns to an active output state.
If having both PSUs active is more efficient than having one PSU in the sleep state, the active PSU can also activate the
sleeping PSU.
The default PSU settings are as follows:
● If the load on the active PSU is more than 50 percent of PSU rated power wattage, then the redundant PSU is switched to
the active state.
● If the load on the active PSU falls below 20 percent of PSU rated power wattage, then the redundant PSU is switched to
the sleep state.
You can configure the hot spare feature by using the iDRAC settings. For more information, see the iDRAC User's Guide
available at Dell.com/idracmanuals.

Removing a power supply unit blank

Prerequisites
Follow the safety guidelines listed in
108 Installing and removing system components
After working inside your system
Safety instructions on page 29.
on page 30.