CPU power status (c-States)

 

CPU power status (c-States)

Generally users seldom notice this status, and usually only notice it when using CPU-Z to monitor clock frequency and voltage. Mobile processors have more C states than desktops. For example, the Core 2 Duo processor (Meron) supports the C0-C4 state, and the desktop Core 2 Duo processing (Conroe) only supports the C1-C0 state.

 

C0 status (activated)

· This is the maximum CPU operating status, in which commands can be received and processed

· All modern processors must support this power consumption state

 

C1 status (suspended)

· You can execute the Assembly command "hlt (suspended)" to enter this state.

· Extremely fast wake-up time! (Just 10 seconds !)

· Reduces CPU power consumption by 70%

· All modern processors must support this power consumption state

 

C2 status (stop allowed)

· The CPU clock frequency and I/O buffer are stopped.

· In other words, the processor execution engine and I/0 buffer have no clock frequency

· In the C2 state, the CPU and platform energy consumption can be reduced by 70%.

· Switching from C2 to C0 takes more than 100 s

 

C3 status (deep sleep)

· Bus frequency and PLL are locked

· The cache is invalid in multiple core systems.

· In a single core system, the memory is disabled, but the cache is still valid

· CPU power consumption can be reduced by 70%, but the platform power consumption is larger than that in the C2 state

· The wake-up time takes 50 minutes.

 

C4 status (deep sleep)

· Similar to C3, but there are two major differences

· First, the core voltage is less than 1.0 V

· Second, data storage in the second-level cache will be reduced.

· The maximum CPU power consumption can be reduced by 98%

· The wake-up time is slow, but does not exceed 1 second

 

C5 status

· The second-level cached data is reduced to zero.

· The wake-up time is over 200 subtle

 

C6 status

· This Is The New Power Consumption management mode in the Penryn processor.

· When the level-2 cache is reduced to zero, the CPU core voltage is lower

· Do not save CPU Context

· Unknown power consumption, close to zero

· Unknown wake-up time

 

 

 

 

 

High computer performance is a double-edged sword. Although it can bring fast data processing performance, the increase in power consumption has become a headache. High power consumption will not only consume a large amount of energy, but also lead to an increase in the chip heat, affecting the stability and life of the electronic chip. So how can we reduce the power consumption of chips and achieve energy saving?

From the perspective of hardware manufacturers, on the one hand, they can reduce energy consumption and heat consumption by improving the chip process. On the other hand, by changing the operating mode of each electronic chip, the dynamic energy saving of the computer can be realized, and different processing loads can be handled with appropriate performance. This method is the energy-saving technology discussed in this article. What are the current mainstream dynamic energy-saving technologies for processors? How can we make full use of these technologies?

◆ Intel C-State Tech

Intel C-State Tech is a deep energy-saving technology added to BIOS by motherboard manufacturers. It automatically adjusts the power status of the processor based on its usage, and then adjusts the voltage, frequency, and power consumption of the processor.

C-State refers to the power consumption and temperature management status of the processor. Commands can be executed only when the processor is activated in the C0 State. In the C1 to CN state, the processor is in a variety of sleep states, sleep can reduce the CPU power consumption. However, in this sleep state, the processor has a wake-up time for restoring to C0. Different C-States consume different wake-up times.

Wake-up time and power consumption in different processor power states: the smaller the power consumption, the longer the wake-up time to return to C0 state.

As shown in the table, the C1 and C2 states can control the power consumption of the processor within 30% of the full-speed running, and quickly respond to the load within a very short wake-up period.

Some Manufacturers' mainboards provide intel C-State Tech support. You can choose whether to enable the technology and control the status of each c-state.

Intel C-State Tech option settings in the motherboard BIOS

　　TIPS:

Because intel C-State Tech also requires the North Bridge Chip and memory to adjust the voltage and frequency when switching the processor status to power-saving mode, therefore, it has high hardware requirements for the entire platform. If the quality of the motherboard is not good or the memory is not good enough, enabling intel C-State Tech will cause frequent windows crashes and other problems. If the computer on the Intel Platform Often crashes, you can check whether this option is enabled in the BIOS of the motherboard.