Hi, I have upgraded the bios on my L590 from 1.21 to 1.24.

Before upgrading I got constant  3.7 GHz when all cores were fully utilized. Now I get 3.65 GHz first, but after a short time it goes down to 3.1 GHz. Moreover when idle, the cpu frequency jumps back and forth from 800MHz to 3.7 GHz. Before the upgrade it was relatively constant at 800MHz when idle.

I am using Linux with the throttling fix https://github.com/erpalma/throttled which worked fine before upgrading the bios. I wasn't able to downgrade the bios.

Is there any way to fix this?

Hi phorse,

Welcome to the Community Forums.

The CPU downthrottling during idle is normal and a power saving feature. If you are unable to perform a BIOS back flash using the step below then I know Windows has ways of turning off Power Throttling in Registry, but alas, I do not know much about Linux. 

BIOS Back Flash
- Completely shut down the device.  
- Press F1 repeatedly on startup to enter BIOS.
- In the "Security" Tab, click "UEFI BIOS Update Option" then set "Secure Rollback Prevention" to "Disabled"
- Click the "Restart" Tab and click "Save Exiting Changes" or Press "F10"
- PC will Restart and enter the Windows Environment.
- Head over to the Support Page for your device.
- Under Drivers & Software, Manual Update, then BIOS section, you can find the latest BIOS version.    
- Expand the BIOS driver with the down arrow. Right Click then select "Copy Link Address"
- Paste it into the URL section of the browser
- Change the nr of the bios version  (ex: 8HCN36WW  to 8HCN35WW or 8HCN34WW) and hit enter.
- Do this in the URL input section of the browser until you find the previous BIOS version to download.
- Right click the file and select "Run as Administrator"
**Note: You can also attach the file to a USB flash drive, boot from USB through BIOS and then run it that way.
**Note: Make sure the AC adapter is connected and that you have at least 30% battery charge when performing this update.

Regards

Voithos