There is this quite annoying bug, which is probably related to Windows 10, which makes mobile CPUs clock down to 0.39 GHz/399 MHz. Just searching on Google for "0.39 GHz". There are so many results with this exact problem.
My brand new Lenovo ThinkPad T15 has this problem as well with its i7-10510U CPU. However, it gets a bit weirder than that. Even when the CPU is running at 100% on all 4 cores/8 threads, Windows still manages to say "nope, this PC is definitely sleeping". Just take a look (although it's at 499 MHz and not 399 MHz here):
As you can see, all cores are maxed out, yet the CPU is still heavily underclocked. The temperature is fine - it rarely hits 90-95 degrees, where throttling would start to occur.
So I did a couple of things:
- Turn performance slider in Windows to Maximum Performance
- Open BIOS and disable CPU Power Management (which has some smart measurements that turns the CPU clock speed and voltage down when it THINKS it's asleep)
That seemed to help and I rarely get stuck at 0.39 GHz again.
HOWEVER, the laptop basically sits in a corner while I work, because I RDP into it from my desktop PC, which has more monitors, better keyboard, and so on. It works great. However, when the screen goes to sleep/turns black, it instantly sets the clock speed to 0.39 GHz again.
So now I have to either choose between having a CPU running at 0.39 GHz OR a CPU running at 4.3 GHz basically all the time, but the screen is turned on at the lock screen, so it might burn in after a while.
I'm tech savvy and I need some answers, so please, fire away. Why is the CPU "sleeping" at extremely low clock speeds, when the CPU hits 100% utilization? Why does Windows 10 or the laptop think it's okay to tell the CPU to "sleep"/preserve power, when the screen is turned off but I am actively using the PC via RDP? Is there a fix to this? So many questions and nobody has the answer, according to the 20+ sites I've went to.