Wrong package power reported by CPU, triggering power throttle

[toki]

Hi,
I have a Lenovo Flex 5 with the i5-1235U processor. The package power it is reporting is constantly around 60 W, which was triggering power throttling and crippling the laptop to where it was unusable - all cores would be set to 399 MHz.
When I use ThrottleStop to increase the PL1 and PL2 limits it runs without problems, but running the TS Bench load the power will show over 100 W at times.
I know that it is not actually using this much, by looking at the battery charge over time as reported by HWmonitor. The battery would drain much faster if the CPU was really constantly using 50+ W.

Has anyone seen this behaviour and if so, what would be the recommended way of addressing it?

 

[unclewebb]

Intel CPUs do not report actual measured power consumption. The power consumption value reported can be off significantly compared to actual power consumption. If the IMON Slope variable is not set correctly, the CPU might report half as much power or it could report twice as much power consumption. There is also a IMON Offset value where the entire power consumption curve can be shifted. If it reports 60W when idle when you think it should show less than 10W, maybe the curve has been offset by 50 or more.

what would be the recommended way of addressing it?

If you believe the value is not accurate, do not use it. Ignore it. Continue using ThrottleStop with PL1 and PL2 set much higher to compensate. ThrottleStop does not have access to the IMON values to try and correct this problem. You can try updating the BIOS but for most laptops, I would recommend not doing this. Some BIOS updates will fix one problem while causing two new problems. It is often times not worth the risk.

 

[toki]

Thanks for the quick reply. I am fairly new to the topic of CPU power allocation and throttling.

What confuses me is that looking at HWMonitor it shows the "IA Cores" power correctly (low when idle and going up to about 50 W when benchmark is running), but the "Package" power is constantly higher than the CPU's Maximum Turbo Power (55 W). Looks like the "Package" power has a baseline around 50 W and then the IA Cores on top of that. The image shows this under "Powers" section.

I am not 'using' this value in any way. I was only using ThrottleStop to troubleshoot the dismal performance. Also, the performance issue only started happening after about 1 year of normal behaviour.

There is no access to advanced BIOS settings on this laptop. While using ThrottleStop to set the PL1 and PL2 settings on boot is an acceptable workaround I am curious what the root cause is and if it is a known issue.

 

[unclewebb]

The cores and package power are calculated separately. The cores might be right while the package might be wrong.

Does ThrottleStop show the same thing? High package power?

Your screenshot shows a significant load on two of the P cores. Try using HWINFO.

Your min package power is only 9W. Open the Task Manager and find out what is running on your computer.

 

[toki]

ThrottleStop shows very similar numbers for PKG power, so does HWiNFO. It shows "System Agent Power" high as well (around 40-50 W) as well as a total power draw on the battery of around 10 W (way less than the package power value, more like what I would expect).

This is a clean factory restore at this point, the only things added are these CPU power tools. It has a bunch of Lenovo stuff by default. But the top things in Task Manager are the Windows Manager, HWiNFO, and such - all at most at 2-5% each. The usage is not a question and should have nothing to do with this wrong Package power issue.

 

[unclewebb]

wrong Package power issue

I know other people have reported the same thing. It always seems to be the System Agent that is reporting high power consumption. I cannot remember ever hearing about a solution. This is likely a bug at the CPU level that would require Intel to release a microcode update which I guess they have not done yet.

At least using ThrottleStop to increase the turbo power limits lets you work around this problem. Most people would never know why their CPU was power limit throttling and under performing during light load.