The Acer C720 Chromebook is a legendary piece of hardware in the “ChromeOS-to-Windows” conversion community. Known for its rugged build and Intel Haswell processor, it remains a popular target for users who want a cheap, portable Windows 10 machine. However, because this device was never intended to run Microsoft’s operating system, installing Windows 10 often leads to two major “deal-breaker” issues: a non-functional touchpad and completely silent audio.
Achieving a fully functional Windows 10 environment on the C720 requires more than just a standard installation; it requires specialized third-party drivers and BIOS modifications. Understanding how to troubleshoot and fix common PC issues is the first step in managing a converted machine like this.
Table of Contents
- The Root Cause: Standard Drivers Won’t Work
- Solving the Audio Issue (Realtek/Intel SST)
- Fixing the Touchpad (Cypress/Elan/Synaptics)
- Essential Auxiliary Drivers
- Summary of Key Takeaways
- Sources
The Root Cause: Standard Drivers Won’t Work
The primary hurdle is that the Acer C720 uses a custom BIOS (Coreboot/SeaBIOS) and specific hardware controllers that Windows does not recognize natively. While Acer provides standard drivers for their Windows-native laptops [1], they do not offer official support for Chromebooks running Windows.
To even begin the driver installation process, the C720 must have its “Write Protect” screw removed from many models and be flashed with Full ROM Firmware (typically from MrChromebox). Without this firmware, Windows will be unable to communicate with the hardware bus that controls the audio and touchpad.
Official drivers from Acer are designed for Windows-native laptops, whereas the C720 uses a custom BIOS (Coreboot) and hardware controllers that Windows does not natively recognize.
You must remove the Write Protect screw and flash the device with Full ROM Firmware, typically from MrChromebox, to allow Windows to communicate with the hardware bus.
Solving the Audio Issue (Realtek/Intel SST)
On a fresh Windows 10 install, the Acer C720 will show “No Audio Output Device is installed.” This is because the Intel SST (Smart Sound Technology) used in the Haswell architecture requires a specific driver bridge that is not included in the Windows Update catalog.
1. The CoolStar Audio Driver
The most reliable solution comes from the independent developer community, specifically CoolStar. They developed a custom driver that enables the Realtek ALC5642 audio codec used in the C720.
Installation: You must enable “Test Signing” mode in Windows 10 (via Command Prompt) because these drivers are not digitally signed by Microsoft.
Result: This restores both the internal speakers and the 3.5mm headphone jack.
2. Monitoring for “Red X” Audio Symbols
If the driver is installed but the audio still fails, it is often due to a conflict with the High Definition Audio Controller in Device Manager. According to user discussions on Reddit, users often need to manually select “Update Driver” -> “Browse my computer” -> “Let me pick from a list” and choose the generic “High Definition Audio Device” to get the bridge working before applying the CoolStar patch [2].
This occurs because the Intel SST (Smart Sound Technology) in the Haswell architecture requires a specific driver bridge not found in the standard Windows Update catalog.
You must enable ‘Test Signing’ mode in Windows via the Command Prompt before installation because these community-developed drivers are not digitally signed by Microsoft.
Manually update the driver in Device Manager by choosing ‘Let me pick from a list’ and selecting the generic ‘High Definition Audio Device’ to establish the bridge.
Fixing the Touchpad (Cypress/Elan/Synaptics)
The C720 was manufactured with different touchpad vendors, most commonly Cypress. Since the touchpad on a Chromebook operates over the I2C bus rather than the standard PS/2 or USB interface, the standard Acer touchpad fixes for Windows laptops generally do not apply here [3].
The I2C HID Solution
To get the touchpad working, you must install a specific I2C Controller driver first. Without the I2C bus driver, Windows cannot “see” the touchpad hardware.
Cypress Drivers: For most C720 models, the Cypress Trackpad driver for Windows 10 is required. Once installed, it enables multi-touch gestures and right-click functionality.
Crosetto/CoolStar Drivers: Again, the community-driven Chromebook Windows drivers are the gold standard.
Keyboard Shortcuts: Unlike standard laptops where
Fn + F7might toggle the pad, converted C720s rely entirely on the driver’s software state.
If you find that the touchpad is still erratic, checking Windows vs. macOS vs. Linux platform comparisons can provide perspective on why certain hardware is more “open” to driver modification than others.
Standard fixes fail because the C720 touchpad operates over the I2C bus instead of the more common PS/2 or USB interfaces used by most Windows laptops.
You must install the specific I2C Controller driver first; without it, Windows cannot detect the touchpad hardware to apply the Cypress or Elan drivers.
No, standard keyboard shortcuts for toggling the trackpad do not work on converted units; the touchpad state is managed entirely through the driver software.
Essential Auxiliary Drivers
Beyond audio and mouse, two other drivers are critical for a stable C720 on Windows 10: 1. Intel Chipset/Graphics: Download the Intel HD Graphics drivers for Haswell directly from Intel. This ensures the screen brightness controls work. 2. Keyboard Remapper: Chromebooks lack a “Windows” key and “Delete” key. Using a utility like SharpKeys or a dedicated Chromebook Keyboard Remapper will allow you to map the “Search” key to the Windows key and the top-row keys to their respective F1-F12 functions.
Download and install the official Intel HD Graphics drivers for the Haswell architecture directly from Intel to enable proper brightness management.
Since Chromebooks lack a native Windows key, use a utility like SharpKeys or a Chromebook Keyboard Remapper to map the ‘Search’ key to the ‘Windows’ function.
Summary of Key Takeaways
Action Plan for Acer C720 Windows 10 Success:
- Preparation: Flash the MrChromebox Full ROM firmware before installing Windows.
- OS Setup: Install Windows 10 (64-bit is recommended for driver compatibility).
- Enable Test Mode: Open Command Prompt as Admin and run
bcdedit /set testsigning onthen reboot. This is mandatory for community drivers. - Audio Fix: Install the CoolStar Realtek Audio driver. If no sound occurs, check the Intel SST Audio device in Device Manager.
- Touchpad Fix: Install the I2C Bus driver first, followed by the Cypress or Elan Touchpad driver.
- Optimization: Use a keyboard remapping tool to fix the missing Windows/Delete keys.
Final Thought: While the Acer C720 requires significant manual “tinkering” to run Windows 10, the result is a highly portable and capable machine. By bypassing official channels and utilizing community-developed I2C and Audio drivers, you can extend the life of this classic Chromebook well beyond its original ChromeOS expiration date.
| Component | Driver Solution | Required Action |
|---|---|---|
| Audio | CoolStar Realtek ALC5642 | Enable Test Signing Mode |
| Touchpad | I2C Bus + Cypress Driver | Install I2C Controller first |
| Graphics/Brightness | Intel HD Graphics (Haswell) | Direct Intel legacy driver install |
| Keyboard | SharpKeys / Remapper | Map Search to Windows key |
The 64-bit version of Windows 10 is highly recommended to ensure maximum compatibility with the specialized community drivers for audio and the touchpad.
Yes, running the command ‘bcdedit /set testsigning on’ and rebooting is mandatory to allow Windows to load the unsigned community drivers required for hardware functionality.