I am trying to play around with the power limit register (MSR_PP0_POWER_LIMIT) available in sandy bridge architecture. The machine is equipped with i5-2500K processors. But after modifying the register, I don't see any impact on the power consumption. I use the energy status register (MSR_PP0_ENERGY_STATUS) to measure the energy consumption and divide it by time spent to get the average power consumption. I get the same power measurement before and after I modify the power limit register.
I tried the same process with one of the Xeon processor and it seemed to work. I can notice the change in the power consumption of the cpu cores.
Does it mean that these registers work only in server class processors and not in desktop processors ?