iamE_D,
Core temperatures respond instantly to changes in load.
Intel’s specification for Digital Thermal Sensor (DTS) response time for Core temperatures is 256 milliseconds, or about 1/4th of a second. Since Windows has dozens of Processes and Services running in the background, it’s
normal to see rapid and random Core temperature “spikes” or fluctuations, especially during the first few minutes after startup.
Any software activity will show some percentage of CPU Utilization in Windows Task Manager, where unnecessary Tray items, Startups, Processes and Services that contribute to excessive spiking can be disabled.
6th Generation processors introduced "Speed Shift" technology in Windows 10, which responds much faster to changes in workload than "SpeedStep" due to having many more Core speed and Core voltage transition levels. This allows the processor to more rapidly complete brief Windows tasks then quickly return to idle, thereby saving energy.
Since 7th through 9th Generation Speed Shift is twice as fast as 6th Generation, some users complain of
Core temperature spikes which can also cause fluctuations in fan RPM at idle. Motherboard manufacturers are implementing BIOS updates that include separate SpeedStep and Speed Shift settings with more flexible fan curves and time delay options.
When the i7-7700K was first launched in January 2017, a very lengthy thread that has 1,110 responses was started in Intel's Forums titled:
Thermal sensor issue i7-7700k? -
https://forums.intel.com/s/question/0D50P0000490E0VSAU/thermal-sensor-issue-i77700k?language=en_US&start=540&tstart=0
The thread's title is very misleading because it wasn't until many dozens of responses later when they began to come to grips with the root cause of the problem, which had nothing to do with any thermal sensor issues. Intel's lame response angered a large portion of the gaming and overclocking communities. It turns out that many users were experiencing exactly the same problems with fan fluctuations at idle that you've described.
Reapplying thermal compound and re-seating your cooler will have no effect on thermal spiking. Workload drives Power consumption (Watts), which in turn drives Core temperatures. This means
spiking is strictly a result of foreground and background software activities. Although fluctuations in Core temperatures at idle can never be eliminated, there are two action you can take to alter thermal and fan behaviors:
First, cleaning up your software will achieve a more "quiet" idle condition, which will minimize spiking.
Second, revisit your fan settings in BIOS to optimize the temperature thresholds at which the fans begin to spin up.
Don't be reluctant to experiment with these settings. It's OK to make large temperature increases in CPU fan thresholds where your fan RPM remains slow and quiet until about 75°C. After you've discovered which settings and values maintain effective cooling during heavy workloads, while allowing fan RPM to remain undisturbed at idle and moderate workloads, you can later dial back and fine-tune the settings.
In addition to temperature thresholds, look for time delay settings, which is sometimes called "hysteresis". Thresholds and time delays can interact with one another, so there's no magic formula. Unfortunately, the key comes down to trial and error. Just work with the settings. Be patient but persistent. You'll find the combination and solve the problem. Consult your motherboard's user manual for where to find these settings.
CT
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