CPU Usage Calculation, Task Manager vs Core Temp

AriGee50 · January 13, 2019

So I have a question that has been plaguing me for some time. I use core temp as a plugin to feed data for temps and for CPU use to my rainmeter modules. Works nicely and I can keep an eye on all my important numbers easily. (Note: A little hi res 4 inch LCD screen makes a wonderful tool for this purpose, chapstick for scale =P)

However, Ive noticed that at the same time as my resource monitor (as fed by Core Temp) is reading about 25% use, windows is estimating my CPU use around 40%

So......WTF?!?!

Who is right? Windows is estimating that with very few things running my CPU use is already over 40%...that seems off. but maybe its not? Who is reading correctly and who needs their glasses checked? And why are they so far apart from each other?

Thanks fellow nerds. please teach me.

Ari

mariushm · January 13, 2019

It's kind of normal.

The measurements aren't done at the same time, one software may take a "snapshot" in the first 100 milliseconds of every second, the other software may take a "snapshot" 500 ms later.

Also, processors these days dynamically adjust their frequencies depending on load and how much load the other cores have. So one software could take measurement when the core is running at 1800 Mhz and half a second later the core could have a tiny bit more work and boost itself at 3 Ghz - the percentages are most likely calculated based on the frequency at the moment of measurement.

Also, the cpu doesn't really tell you how busy each core is, that's calculated over periods of times... one software could compute the load and tell you the average over the previous 2 seconds, another software could average just the last second or half a second.

AriGee50 · January 14, 2019

but would that really explain why the two are so far apart? I mean windows can often estimate CPU use as double what core temp does? and if that is all it is, which is a better representation of whats really going on? because if my computer is using at least 30% CPU AT IDLE...im in trouble...

LogicalDrm · January 14, 2019

11 hours ago, AriGee50 said:

but would that really explain why the two are so far apart? I mean windows can often estimate CPU use as double what core temp does? and if that is all it is, which is a better representation of whats really going on? because if my computer is using at least 30% CPU AT IDLE...im in trouble...

Can you post pic where you have all of these showing at the same time? And then another with task manager processes tab with sorting based on either CPU or RAM usage. The percentages are same on those two images, with scaling being odd with Rainmeter.