Latest Windows 10 update locked my CPU clock speed

[MyNameIsAldrin]

Hello, let me explain this situation. 

 

Specs

Asus VivoBook F510UA-AH51

Windows 10 Home 64bits  10.0.18363 Build 18363

i5-8250U

8GB DDR4 RAM

128GB Adata SATA SSD (System)

1TB Toshiba HDD (Storage, Pagination)

 

Context

 

About 3 to 4 days ago i updated my laptop via windows update, just clicked update and restart and all of that, i forgot about that a just went with my day as usual. While browsing i noticed that my computer felt very slow. i checked the task manager and didn't found anything weird, the next day it was still as slow and i noticed that task manager was reporting my clock speed at 1.8GHz. Weirdly enough i noticed it while i was on battery, which usually limits the clock speed to 0.8GHz or even less depending on the task. I plug in the laptop to the wall and clock speed remains the same, locked in 1.8GHz.

I Checked windows energy options, battery options and everything was as usual. computer was on performance power plan and there was no software change at all (other than the windows update). Googled everything but no luck. I proceed to boot into linux, since i have both OS installed and to my surprice Ubuntu runs smooth and lscpu reports the correct clock speed with the CPU under load. 
 

Back in Windows i use CPU-Z to measure CPU score and compare it to other i5-8250U (maybe this was just a "cosmetic" bug?) to my surprise (or not) my CPU score was about 110 ~ while the reference i5-8250U  has a score of more than 400 (single core performance).

 

Windows doesn't have enabled the option to rollback this update, my computer is SUPER slow and i dont know what happened or what to do. (Other than using linux i guess, but i need windows for work)

 

TL;DR

 

Intel i5-8250U is locked into 1.8GHz no matter the load or energy state (battery vs plugged in) since last windows update, only on windows (on ubuntu clock goes to the expected >3GHz)

 

 

Clock speed while running Prime95 but no matter the load type it stays there, plugged in or on battery.

 

 

On linux while running sysbench it goes for the rated >3GHz clock speed

[unclewebb]

An 8250U should show 4 Cores and 8 Threads in CPU-Z.

 

http://valid.x86.fr/fd1wrk

 

The Task Manager is reporting 2 Cores and 4 Threads.  Looks like the Windows update disabled half of your CPU.  This also screws with Turbo Boost when this happens.

 

Open up msconfig and make sure the Number of processors box is clear.  After you do that, reboot so Windows can find the rest of your CPU.

 

[MyNameIsAldrin]

9 hours ago, unclewebb said:

An 8250U should show 4 Cores and 8 Threads in CPU-Z.

 

http://valid.x86.fr/fd1wrk

 

The Task Manager is reporting 2 Cores and 4 Threads.  Looks like the Windows update disabled half of your CPU.  This also screws with Turbo Boost when this happens.

 

Open up msconfig and make sure the Number of processors box is clear.  After you do that, reboot so Windows can find the rest of your CPU.

 

Oh my god... i can't believe this solved it. How come microsoft disables cores on my computer out of the blue? 

 

Thank you so much !!!