Lenovo with 7500u - low load at 3.5GHz, but 2.7Ghz when high load?

[klchan.kalam]

Hi I just got a new Lenovo laptop (720s), with 7500u CPU and 16GB ram.

I find the cpu freq at 2.7 when windows starts, but goes to 3.5 on no load. Then it goes to 2.7 again on load (do some program compilation).

I'm not sure why this happens, to me, putting some work to the cpu should make the freq goes up instead of down.

If this is normal, what'd the reason be?

 

[Sohom]

It seems like cpu throttling, it happens when temps are critically high, the cpu throttles to protect it from damages. Check the temps with HWINFO (https/www.hwinfo.com/download.php).

 

[rgd1101]

https/ark.intel.com/products/95451/Intel-Core-i7-7500U-Processor-4M-Cache-up-to-3_50-GHz-
3.5 is max turbo, it depend on the TDP, when onload, it will be over TDP to keep at 3.5

 

[ThomasKK]

Hi, this is completely normal:

3.5GHz is the maximum turbo-speed of i7-7500u, which only applies to 1 core (LinusTechTips has a video on youtube explaining turbo speeds, that video should explain it to you), but long story short - only 1 core can run at 3.5GHz leaving other core almost idle'ing, which is very useful in single-core applications and thats why Intel's CPUs have insanely high single-core performance in CPU benchmarks (the chip gives the majority of electrical power just to a single core), but when you launch a program that can utilize more than 1 CPU core, the CPU will divide the electric power between 2 cores making them work simultaneously as fast as they can with given TDP and cooling solution, which is usually named a base speed, which in your case is 2.7GHz. Hope this helps!

EDIT: here is the link to the video - https/youtu.be/H4ryOzIZvpQ