Lenovo IdeaPad Slim 3i Gen 8 Screen Brightness Not Working Fix
Core i3-1305U
Display Fix
When the brightness keys (Fn + F5 / F6) do not change screen brightness on the Lenovo IdeaPad Slim 3i Gen 8 (Core i3-1305U), the cause is almost always a display driver issue, an outdated BIOS, or an incorrect adaptive brightness setting. The following steps fix brightness control reliably.
Update the Intel display driver from Lenovo Support
Go to Lenovo Support, find IdeaPad Slim 3i Gen 8, and download the latest Intel UHD Graphics driver. Install it and restart. An outdated Intel graphics driver is the most common cause of non-functional brightness keys on this model, particularly after a Windows cumulative update.
Disable adaptive brightness
Go to Control Panel → Power Options → Change plan settings → Change advanced power settings. Expand Display → Enable adaptive brightness and set it to Off for both On battery and Plugged in. Adaptive brightness can override manual brightness changes and make it appear as if the keys are not working.
Adjust brightness from Windows Settings
Go to Settings → System → Display and move the Brightness slider. If the slider is present but does not change the brightness, the Intel display driver needs reinstallation. If the slider is missing entirely, the display driver is not installed or is not recognizing the built-in panel.
Update the BIOS
Install the latest BIOS from Lenovo Support via Lenovo System Update. Some early BIOS versions for the IdeaPad Slim 3i Gen 8 do not initialize the backlight control interface correctly, resulting in the brightness slider having no effect even when the Intel driver is up to date.
Install the Lenovo Smart Display app
Search for Lenovo Smart Display or check Lenovo Vantage for display management tools. Some IdeaPad models require a Lenovo display management component to be installed for brightness hotkeys to function. Installing it alongside the Intel driver restores Fn key brightness control.
Ainul, Alor Setar: “The brightness keys on my IdeaPad Slim 3i stopped working after a Windows update. Reinstalling the Intel UHD Graphics driver from Lenovo Support and disabling adaptive brightness fixed both issues immediately.”
Frequently Asked Questions
Why did the brightness keys stop working after a Windows Update?
Windows Updates sometimes replace the OEM Intel graphics driver with a generic Microsoft version that does not support backlight control on the IdeaPad Slim 3i. Reinstall the Lenovo-packaged Intel driver from Lenovo Support to restore brightness key functionality.
What is the keyboard shortcut for brightness on the IdeaPad Slim 3i Gen 8?
The brightness shortcut on the IdeaPad Slim 3i Gen 8 is Fn + F5 to decrease and Fn + F6 to increase. If the Fn lock is engaged (look for a lit Fn lock indicator), press Fn + Esc to toggle Fn lock off and restore the hotkey behavior.
Can Content Adaptive Brightness Control (CABC) affect manual brightness on this laptop?
Yes. CABC is a panel-level feature that adjusts brightness based on screen content, and it can override manual settings on some IdeaPad displays. In Intel Graphics settings, look for a Display Enhancement or CABC option and disable it if the brightness fluctuates unexpectedly.
The brightness slider is completely missing from Display Settings — what should I do?
A missing brightness slider means Windows does not recognize the built-in display as brightness-controllable, usually because the Intel display driver is not installed. Open Device Manager, check for Display Adapters, and install the Intel UHD Graphics driver from Lenovo Support to restore the slider.
Ryan holds a Computer Science degree and has over 20 years of hands-on experience with PC hardware, software, and driver troubleshooting. He is the author behind softwaredriverdownload.com, where he helps everyday users fix driver issues quickly and accurately. Ryan has personally tested most of the fixes on this site across a range of Windows 10 and Windows 11 machines.
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