ASUS X540UBR Rev 2.0 onboard RAM Disable

Disabling Onboard RAM on the ASUS X540UBR Rev 2.0: A Hardware-Level Hack

The ASUS X540UBR Rev 2.0 is a budget-friendly laptop that comes with a mix of onboard (soldered) and upgradable RAM via a SO-DIMM slot. While the design suits most users, hardware tinkerers and modders sometimes face a limitation: the soldered RAM can't be disabled via the BIOS, even with advanced firmware mods.

This limitation becomes especially frustrating when the onboard RAM is faulty or when performance tuning requires relying solely on higher-capacity or faster SO-DIMM modules.

Why Disable the Onboard RAM?

There are a few scenarios where disabling onboard RAM becomes desirable:

1. Faulty soldered RAM that causes crashes or boot failures.
2. Upgrading performance, where the soldered RAM limits dual-channel configurations or max capacity.
3. Custom setups that need complete control over memory behavior.

Unfortunately, ASUS does not offer a BIOS-level toggle to disable onboard RAM in the X540UBR Rev 2.0, which brings us to a more drastic—yet effective—solution.

Hardware-Level RAM Disable: A Motherboard Mod

Disclaimer:

    This mod is for advanced users only. It requires soldering experience, a steady hand, and a full understanding of motherboard schematics. You risk permanently damaging your device. Proceed at your own risk.

Through community experimentation and analysis of the board's layout, a hardware method to disable the onboard RAM has been identified. It involves shifting resistor positions on the motherboard. 

Required Mod:

To completely disable the onboard RAM, perform the following resistor swaps:

1. Shift resistor R2184 to R2185
2. Shift resistor R2180 to R2181

These tiny surface-mount resistors control the addressing lines or power delivery to the onboard RAM modules. By shifting them, you're essentially redirecting or breaking the connection needed for the system to recognize the soldered memory.

What Happens After the Mod?

Once completed, the system should:

1. Ignore the onboard RAM entirely during POST and boot.
2. Recognize only the SO-DIMM slot RAM, allowing for full utilization of the upgrade.

This can be verified in the BIOS and from within the operating system, where the total memory reported will reflect only the SO-DIMM module installed.

Final Thoughts

Disabling onboard RAM in the ASUS X540UBR isn't officially supported, but for those confident in hardware-level modifications, the resistor shift method provides a functional workaround. Whether you're troubleshooting a bad module or optimizing your laptop for a specific use case, this mod opens the door to better flexibility.

Have you tried this hardware mod or a similar one on another model? Let us know your experience below!