ASUS ROG Strix Scar 16 G634 • AMD Ryzen 9 7945HX • Windows 11
MUX Switch Not Working Fix
The ASUS ROG Strix Scar 16 G634 is a flagship gaming laptop with the AMD Ryzen 9 7945HX and NVIDIA GeForce RTX 4090. Its MUX Switch (Multiplexer Switch) bypasses the AMD iGPU and connects the NVIDIA dGPU output directly to the display, improving gaming performance by up to 15-25%. When the MUX Switch does not appear or does not change after clicking in Armoury Crate, specific system conditions block the switch.
Fix 1: Ensure Armoury Crate Is Updated
Open MyASUS or the Armoury Crate app and check for updates. The MUX Switch UI and backend service require the latest Armoury Crate version on the ROG Strix Scar 16 G634. An outdated Armoury Crate may show the MUX toggle but fail to apply it or may not show the option at all.
Fix 2: Update BIOS
Visit ASUS Support and download the latest BIOS for the ROG Strix Scar 16 G634 (G634JZ or G634JY depending on GPU configuration). BIOS updates on the Scar 16 include MUX Switch reliability improvements and NVIDIA dGPU direct mode initialization patches. Install while plugged in via MyASUS BIOS Flashback or EZ Update.
Fix 3: Check NVIDIA Driver Support for MUX
The ASUS MUX Switch requires a compatible NVIDIA driver to activate dGPU direct mode. Older NVIDIA driver versions may not support ASUS MUX on the Ryzen 9 7945HX + RTX 4090 combination. Update to the latest NVIDIA Game Ready Driver from NVIDIA.com before testing the MUX Switch.
- In NVIDIA Control Panel, verify the display is connected to the NVIDIA GPU (shows under Display > Set up G-SYNC)
- After MUX Switch to dGPU mode, G-SYNC should be available on the internal display
- If MUX is in iGPU/Optimus mode, G-SYNC is not available on the internal display
Fix 4: Reinstall Armoury Crate Service
If the MUX Switch option is missing from Armoury Crate entirely, uninstall Armoury Crate completely via Programs and Features, restart, then download and install the latest version from ASUS Support for the G634. The Armoury Crate system service must be running for the MUX hardware interface to be accessible from the software.
“My ROG Strix Scar 16 MUX Switch was not working — dGPU mode showed no improvement. After updating BIOS and Armoury Crate, and doing a full shutdown (not just restart), the MUX Switch worked correctly and I gained about 20 FPS in most games.” — Fadzlan Ramli, competitive FPS gamer
Frequently Asked Questions
Ryan holds a Computer Science degree and has spent over 15 years troubleshooting Windows hardware and driver issues across major laptop brands. He writes practical, step-by-step guides for everyday users at softwaredriverdownload.com.
Why is the MUX Switch not working on the ASUS ROG Strix Scar 16 G634?
The MUX Switch on the Scar 16 G634 requires a full cold-start shutdown (not sleep or restart) to activate, an updated Armoury Crate application, a compatible BIOS version, and a recent NVIDIA driver. Update all components and perform a complete shutdown and power-on to apply the MUX Switch state change.
What does the MUX Switch do on the ASUS ROG Strix Scar 16 G634?
The MUX Switch bypasses the AMD Ryzen 9 7945HX integrated GPU and connects the NVIDIA GeForce RTX 4090 directly to the laptop display. This eliminates the overhead of routing NVIDIA GPU output through the AMD iGPU, improving gaming frame rates by approximately 15-25% depending on the game and resolution.
Does enabling MUX Switch on the Scar 16 G634 affect battery life?
Yes. In MUX dGPU mode, the NVIDIA RTX 4090 is always active as the primary GPU, consuming significantly more power than Optimus mode where the AMD iGPU handles display output for non-gaming tasks. For maximum battery life, set MUX to iGPU/Optimus mode during non-gaming use.
Is the MUX Switch on the ASUS ROG Strix Scar 16 G634 hardware or software?
The MUX Switch is a hardware multiplexer physically switching the display connection between the AMD iGPU and NVIDIA dGPU. The switch state is controlled via BIOS and Armoury Crate software. Because it is a hardware switch, a full power cycle is required to change the physical signal routing.
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