DELL
G15 5535
Ryzen 5 7640H
Screen Brightness Not Adjusting Fix
Screen brightness not adjusting on the Dell G15 5535 Ryzen 5 7640H means the keyboard Fn + brightness keys do not change display brightness, the brightness slider in Windows Settings is grayed out or missing, or brightness resets after restart. The G15 5535 uses AMD Radeon 760M integrated graphics with an optional NVIDIA discrete GPU. Brightness control requires the correct AMD display driver and Windows display configuration for proper brightness slider functionality.
Brightness slider missing
The AMD display driver is missing the monitor brightness control. Reinstall the AMD display driver from Dell Support for the G15 5535.
Fn + brightness keys not working
The Dell Optimizer or Alienware Command Center hotkey service is not running. Reinstall Dell drivers from Dell SupportAssist.
Fix: Reinstall AMD Display Driver from Dell SupportAssist
Open Dell SupportAssist and run a full driver scan. Install the pending AMD Radeon display driver for the Dell G15 5535. Alternatively, download the AMD display driver for the G15 5535 (Model P38E) from Dell Support. The Dell-certified AMD driver includes brightness panel control settings for the G15 5535 FHD 165Hz or QHD 240Hz panel. A generic AMD driver from AMD.com may not register the panel brightness control correctly with the Windows Display Configuration API, causing the brightness slider to be missing or inactive.
Per Hazwan Zainal, physics student using Dell G15 5535 for simulation work: “Brightness slider disappeared from Settings on the G15 5535 after a Windows Update that also updated the AMD driver. Using Dell SupportAssist to reinstall the Dell-certified AMD driver restored the brightness slider and Fn brightness keys immediately.”
Fix: Disable AMD VARI-BRIGHT and CABC
Open AMD Software: Adrenalin Edition → Gaming → Display. Disable VARI-BRIGHT. Also open Windows Settings → System → Display → Brightness and turn off Change brightness automatically and Help improve battery. AMD VARI-BRIGHT and Windows CABC adjusting brightness automatically can override manual Fn key brightness changes, making the panel appear to not respond to brightness adjustments. Disabling both allows manual Fn + brightness key control to function as the sole brightness adjustment mechanism.
Fix: Update Dell BIOS and Embedded Controller
Download and install the latest BIOS for the Dell G15 5535 (Model P38E) from Dell Support. BIOS updates include embedded controller firmware revisions that handle the Fn key mapping for brightness keys on the G15 5535. An outdated EC firmware can cause Fn + brightness keys to send incorrect key codes, which the AMD driver panel backlight controller does not recognize as brightness adjustment commands.
Frequently Asked Questions
Why is screen brightness not adjusting on Dell G15 5535 Ryzen 5 7640H?
The AMD display driver is missing panel brightness control, AMD VARI-BRIGHT is overriding manual adjustments, or the embedded controller firmware needs updating. Reinstall the AMD display driver from Dell SupportAssist, disable AMD VARI-BRIGHT, and update BIOS from Dell Support for the G15 5535 Model P38E.
How do I adjust screen brightness on Dell G15 5535?
Use Fn + F6 to decrease brightness and Fn + F7 to increase brightness on the Dell G15 5535 keyboard. The brightness slider is also accessible in Windows Settings System Display. Alternatively, the Windows Action Center (Win + A) has a brightness slider at the bottom of the panel.
Why does Dell G15 5535 screen brightness reset after restart?
Windows Fast Startup resumes from a hibernated session rather than a clean boot, and the AMD display driver panel control may not reinitialize the brightness level correctly from the hibernated state. Disable Fast Startup in Power Options System Settings to force a clean boot and test whether brightness persists correctly after a full restart.
Does Dell G15 5535 support HDR display?
HDR support depends on the specific panel variant. The standard FHD 165Hz panel does not support HDR. Some QHD 240Hz configurations may support HDR depending on the panel assembly used in the specific production run. Check Windows Settings System Display to see if the HDR option is available for your G15 5535 panel.
Conclusion
Screen brightness not adjusting on the Dell G15 5535 Ryzen 5 7640H is fixed by reinstalling the Dell-certified AMD display driver from Dell SupportAssist, disabling AMD VARI-BRIGHT in AMD Software, and updating the BIOS from Dell Support for the G15 5535 Model P38E. Use Fn + F6 and F7 for brightness control. Disable Windows CABC and AMD VARI-BRIGHT if automatic brightness overrides are preventing manual brightness key control from working correctly.
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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