Why does my CPU frequency keep jumping between 400 MHz and 1.7 GHz?
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MellowOrbit_27
My Intel Core i5-13400F frequently changes between roughly 400 MHz and 1700 MHz, even when the computer is mostly idle. Is that normal? This started around the same time my case fans suddenly became stuck at 100% until I adjusted them manually in MSI Center. The CPU cooler seems to be working properly, and temperatures stay around 32–45°C depending on what I'm doing. I'm also concerned that unusual CPU activity could indicate hidden cryptocurrency-mining malware. The frequency does increase during gaming and other demanding workloads, but I wanted to make sure the idle fluctuations aren't a problem.
Answers
That kind of fluctuation is normal. Modern CPUs lower their clocks and voltage when they have little work to do, then raise them briefly whenever Windows or a background process needs CPU time. The important thing is whether temperatures get too high or the processor stays stuck at a low speed during demanding tasks. Thermal throttling usually becomes a concern around 95–100°C, so your 32–45°C readings look healthy.
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The i5-13400F has both performance cores and efficiency cores, each with different clock ranges. Its efficiency cores have a base frequency around 1.8 GHz, so seeing approximately 1.7 GHz while the system is idle is expected. The processor also drops to much lower idle speeds, such as 400 MHz, to save power. It should boost well beyond 1.7 GHz when running demanding software—up to about 4.6 GHz on the performance cores—so only investigate further if it never boosts under load. Frequency changes by themselves aren’t evidence of a hidden miner.
MellowOrbit_27: It definitely boosts higher when I’m gaming or running several programs. Since the higher readings only appeared while idle, it sounds like the normal behavior of the efficiency cores.
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MellowOrbit_27: That makes sense. I was worried because it was happening while the computer was idle, but it reaches much higher speeds during games and other intensive tasks.