Power Supply Units; Hot Spare Feature - Dell Precision Rack 7910 Owner's Manual

NOTE: Tighten the screws diagonally opposite to each other. Do not over-tighten the heat
sink retention screws when installing the heat sink. To prevent over-tightening, tighten the
retention screw until resistance is felt, and stop once the screw is seated. The screw tension
should be no more than 6 in-lb (6.9 kg-cm).
1. Install the cooling shroud.
2. If applicable, install the PCIe card.
3. If applicable, install the cooling fan assembly.
4. Follow the procedure listed in
5. While booting, press <F2> to enter the System Setup and check that the processor information
matches the new system configuration.
6. Run the system diagnostics to verify that the new processor operates correctly.

Power supply units

Your system supports:
• Two 1100 W AC power supply modules
NOTE: Titanium power supply unit is nominally rated for 200 VAC to 240 VAC input only.
NOTE: When two identical power supplies are installed, power supply redundancy (1+1 – with
redundancy or 2+0 – without redundancy) is configured in system BIOS. In redundant mode, power
is supplied to the system equally from both power supplies when Hot Spare is disabled. When Hot
Spare is enabled, one of the PSUs will be put into standby when system utilization is low in order to
maximize efficiency.
NOTE: For AC power supply units, use only power supply units with the Extended Power
Performance (EPP) label on the back. Mixing power supply units from previous generations of
servers can result in a power supply unit mismatch condition or failure to power on.

Hot Spare feature

Your system supports the Hot Spare feature that significantly reduces the power overhead associated
with power supply redundancy.
When the Hot Spare feature is enabled, one of the redundant power supplies is switched to a sleep state.
The active power supply supports 100% of the load, thus operating at higher efficiency. The power supply
in the sleep state monitors output voltage of the active power supply. If the output voltage of the active
power supply drops, the power supply in the sleep state returns to an active output state.
If having both power supplies active is more efficient than having one power supply in a sleep state, the
active power supply can also activate a sleeping power supply.
The default power supply settings are as follows:
• If the load on the active power supply is more than 50%, then the redundant power supply is switched
to the active state.
• If the load on the active power supply falls below 20%, then the redundant power supply is switched
to the sleep state
After working inside your system.
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