White Paper

Dell Power Center’s Power Policies for 12
th
-Generation Servers
6
Setting an Efficient Capping Value
It is important to set an efficient power cap value for each server. While setting the value too high is
inefficient, setting the cap value too low will impact performance and prevent the server from carrying
out its computational workload effectively. Having the real-time power usage data from Power Center
is a good starting point for setting an efficient capping value on the server. Power Center also displays
the server’s operational power range based on data leveraged from the iDRAC power management
interface. During the server’s power-on self-test (POST), the iDRAC power management function will
determine the highest possible power consumption of a server by executing a measurement test of
power consumption under a simulated maximum load, resulting in the upper power limit of the
operation of the server as seen in Power Center. Power Center also collects measurement data over
time, specifically the minimum power usage for the sampling interval, resulting in the lower power
limit of the operation of the server. Power Center uses these two values as a power capping range for
the server, shown to the user during power cap setup.
Figure 1 shows these key values. The capping value can be set anywhere within the power operation
range, but the recommended setting is between the average power consumption and the upper bound
value.
Figure 2 shows how these values are displayed in Power Center. Power Center will not allow the
capping value to be set outside the lower-bound and upper-bound values.