HP ProLiant DL280 HP Power Capping and HP Dynamic Power Capping for ProLiant s - Page 4

Figure 1. Power use in a typical server Typical Server Power Usage Base Load 13% Hard Drives 4% PCI Slots 15% Processor 33% Memory 28% Fans 7% Processor P-states Processor performance states, or P-states, provide a quick and effective mechanism for adjusting processor power consumption and performance. Both Intel® and AMD® processors support using P-states to decrease processor power consumption by lowering the processor's core frequency and voltage. Tables 1 and 2 list some of the P-states available with different processors. Table 1. P-states of the Intel Xeon 5160 processor P-state P0 P1 P2 P3 Core Frequency 3.0 GHz 2.66 GHz 2.33 GHz 2.0 GHz Table 2. P-states of the AMD Opteron 2220 processor P- state P0 P1 P2 P3 P4 P5 P6 Core Frequency 2.8 GHz 2.6 GHz 2.4 GHz 2.2 GHz 2.0 GHz 1.8 GHz 1.0 GHz Clock throttling Clock throttling is another method for lowering processor power consumption. Depending on the processor model, the system BIOS can either reprogram the processor to run at a lower frequency or modulate the processor between running periods and stopped periods. Both methods have the same net effect of lowering the processor's overall power consumption below the levels available using P-states. The chart in Figure 2 illustrates the relationship between consumed power and overall performance when using P-states and clock throttling to control server power. Using P-states clearly provides greater power reduction for a smaller loss in performance. However, using P-states can lower power consumption only to a certain point. Reducing consumption below that point requires the use of clock throttling. 4