Any software to see what's triggering various C States?

Here's what my i5-8250U looks like every 4 out of 5 seconds when idle.



And on every fifth second, the C3 state jumps to about 30-40% for a second, reducing C8 state percentage, causing package power to go up for a second.


Why?


It's been like this ever since I got my computer - on Windows 1703, 1709, and 1803. Currently not on any Insider Builds. It's a steady rhythm, every five seconds on the dot it spikes up. Then returns to normal.

I've tried a clean install using only OEM drivers, the issue still pertains. A clean installation of windows, and the issue doesn't go away. I'm going to assume and hope that it is a driver issue, but then which one? Is there any software to see what is triggering C states to be higher?

As well, when I close a program, such as Edge, Chrome, even Task Manager, the C state remains at C3 for 3 seconds exactly (PKG power about 1.4W) until C3 states return to normal (0%) and C8 states rise to about 80%. Idling package power for the 8250U is 0.4W. It shouldn't be spiking to 0.7 or 0.8W. C3 states should not be spiking.

Also, assuming ThrottleStop is reporting the correct C state limit, can I check what is stopping the laptop from reaching C9?

Technically, I'm 3 BIOS versions out of date. But newer BIOSes for my laptop disable undervolting, something I absolutely need. Could it be a BIOS issue?

 

Try opening up the Windows Resource Monitor. It has a list of running processes. You might find something in there that jumps up at the same 5 second frequency.

Just out of curiosity, enable Intel Turbo Boost (clear the Disable Turbo box) and set the EPP to 0. Running the CPU at full speed allows the CPU to process background tasks quickly and get back into one of the deeper C states for a longer percentage of time. Part of the Windows 10 design is to group tasks if possible so the CPU can quickly burst, get stuff done, and then get back and spend more time in a low power C state.

With Resource Monitor, see if you can kill any running tasks that are sucking up CPU cycles.

ThrottleStop is a pretty efficient monitoring tool but even it has to wake up your CPU on a continuous basis to monitor what it is doing. To lean it down as much as possible, push the Stop Data button on the main screen to make it more efficient before opening up the C State data window.

SysInternals has some great free tools for hunting stuff down. Their tools were so good that Microsoft bought them.

Process Explorer 16.21
https://docs.microsoft.com/en-us/sysinternals/downloads/process-explorer

Process Monitor 3.50
https://docs.microsoft.com/en-us/sysinternals/downloads/procmon

Of course it is.

You can also try using HWiNFO but I think it monitors too much stuff so it will interfere more with C state residency time. At least this might give you something to compare ThrottleStop to.

 

Having the CPU stuck to 3.4GHz returns the same behaviour. Resmon, Process explorer and process monitor don't return any data that jumps out at regular 5 second intervals. Thx for your help though