Intel Turbo Boost questions

[RFras2]

Hello, we wanted to ask the following 2 questions regarding Intel Turbo Boost (we are using an i7 8700K CPU, where base clock = 3.7 Ghz, the CPU has "not" been overclocked):

1. Assuming the CPU is within its thermal and electrical limits, if "CPU Usage" quickly increases from 2% to 100% within 1 microsecond how long (in microseconds) does it take on average for the Intel Turbo boost to kick in and reach the maximum CPU Turbo frequency of 4.7 GHz?

2. We are using a CPU monitoring tool and see that even when "CPU Usage" is around 20% all 4 cores are going in and out of Turbo Boost mode every 1 second, is this normal behavior? We thought that the "CPU Usage" (as seen in Windows Task Manager) had to be close to 100% for the Turbo Boost mode to kick in (assuming the CPU was within its thermal and electrical limits at all times), is this correct?

When we say CPU Usage is at 20% we mean that CPU Usage for CPU0 = 20%, CPU1 = 20%, ........, CPU12 = 20%, with Intel HT enabled.

Many thanks in advance.

Regards,

Rod

[idata]

Hello Rocket_13,

Thank you for joining the Intel Community Support.I would like to know where you are getting this information from. Please provide the processor monitoring tool (s) you are using. Does this happen if you test another system/processor?Intel® Turbo Boost Technology automatically allows processor cores to run faster, and it depends on a number of factors such as type of workload, number of active cores, temperature, among others.Keep in mind that these results may vary depending on environment and platform desing, too.Wanner G.

[RFras2]

Thank you for your reply. We are using the "Argus Monitoring" program to monitor "CPU frequency" (and whether Turbo Boost has been activated) in real-time. We are using Windows Task Manager to monitor "CPU Usage" in real-time. Yes this behavior happens on multiple computers. The main question we have is as follows: If CPU Usage is 4% in Windows Task Manager can Intel Turbo Boost still be activated, or must CPU Usage be 100% before Turbo Boost can kick in?

As you can see in the attached ScreenShot below, CPU usage was 4% but the 2 cores were actually running in Turbo Boost mode, where Core 1 was running at 2893 GHz frequency (vs base clock of 2500 GHz) and Core 2 was also running at 2893 Ghz frequency which means that Turbo Boost had kicked in and was active. We thought that CPU Usage had to be 100% before the Turbo boost kicks in? Is this correct?

Thank you in advance. Regards, Rod.

[idata]

Hello Rocket_13,

Thank you for your response. CPU usage, or workload, is one of the factors that allows the processor to enable higher performance with Intel® Turbo Boost. However, other factors can also determine when Intel® Turbo Boost technology is enabled such as the estimated power consumption and temperature of the processor. For example, an algorithm in the processor calculates this depending on power management and BIOS settings.It is also worth mentioning that the number of active cores at any given instant dictates the upper limit of Intel® Turbo Boost Technology. Intel® Turbo Boost technology can be enabled with any number of cores or logical processors enabled and active. Wanner G.

[RFras2]

Does "CPU Usage" have to be 100% for Turbo Boost to be activated?

[idata]

Hello Rocket_13,

Not necessarily. CPU utilization is taken into account when enabling Intel® Turbo Boost, but it does not have to be running at 100% to enable this technology. Wanner G.

[RFras2]

Thanks Wanner. Much appreciated. Just one other question:

If "CPU Usage" spikes to 100%, how long (in nano-seconds) does it take for Intel Turbo Boost to kick-in?

Regards,

Rod

[idata]

Hello Rocket_13,

Because this question is very specific, and it may vary from system to system, I will do further research to find out if I can provide a detailed answer about it.Are you developing hardare/software?Wanner G.

[RFras2]

Thank you Wanner. Much appreciated. Yes, we are developing software, and also building a computer to properly run the custom software.

[idata]

Hello Rocket_13,

Thank you for your response. I will keep you updated. Wanner G.

[idata]

Hello Rocket_13,

Because you are developing software, you can go to our Intel® Developer Zone to find additional information and connect with other developers, too. https://software.intel.com/en-us/supportI hope this helps.Wanner G.