How to Disable CSM in BIOS (And Why It Matters for Your System)

If you've been digging into your BIOS settings — maybe to install Windows 11, enable Secure Boot, or get the most out of an NVMe drive — you've probably run into CSM, or the Compatibility Support Module. Disabling it sounds simple, but the process varies depending on your motherboard, and the consequences of doing it wrong can leave you staring at a blank screen. Here's what you actually need to know.

What Is CSM and What Does It Do?

CSM (Compatibility Support Module) is a component of the UEFI firmware that emulates the older Legacy BIOS boot environment. It was introduced to bridge the gap between modern UEFI motherboards and older operating systems, storage devices, and hardware that weren't designed with UEFI in mind.

When CSM is enabled, your system can boot from MBR (Master Boot Record) partitioned drives and support older graphics cards, peripherals, and OSes that don't understand UEFI natively. When it's disabled, your system operates in pure UEFI mode, which unlocks features like:

• Secure Boot — a security standard that verifies bootloaders haven't been tampered with
• GPT (GUID Partition Table) boot support — required for drives larger than 2TB used as boot drives
• Fast Boot and improved startup times
• Windows 11 compatibility — Microsoft requires Secure Boot to be enabled, which in turn typically requires CSM to be off

Think of CSM as a translator for old hardware. When you no longer need that translator, disabling it lets your system speak fluent UEFI.

Why You Might Need to Disable CSM

The most common reasons people disable CSM include:

• Installing or upgrading to Windows 11, which requires Secure Boot and TPM 2.0
• Enabling Secure Boot on a Windows 10 machine for improved security
• Fixing GPU issues on newer discrete graphics cards that expect UEFI GOP (Graphics Output Protocol) support
• Maximizing NVMe SSD performance, as some drives run better in full UEFI mode
• Resolving boot conflicts when a system with both a new and old drive gets confused about which to prioritize

How to Disable CSM in BIOS: Step-by-Step

The exact steps differ by manufacturer — ASUS, MSI, Gigabyte, ASRock, and HP/Dell/Lenovo each lay out their BIOS interfaces differently — but the general process follows the same logic.

Step 1: Enter Your BIOS/UEFI

Restart your computer and press the appropriate key during POST (the first splash screen). Common keys:

Step 2: Find the CSM Setting

CSM is usually buried in one of these menus depending on your board:

• Boot tab → Boot Mode, CSM Configuration, or Launch CSM
• Advanced tab → CSM Configuration
• Security tab (on some OEM machines like HP or Dell)

Look for options labeled "CSM", "Launch CSM", "Boot Mode", or "UEFI/Legacy Boot".

Step 3: Disable CSM ⚙️

Set the CSM option to Disabled or change the Boot Mode from "Legacy + UEFI" to "UEFI Only". On some boards you'll see sub-options for storage, video, and other devices — set all of these to UEFI before disabling the main CSM toggle.

Step 4: Enable Secure Boot (If Required)

Once CSM is off, the Secure Boot option typically becomes available or stops being grayed out. If you're preparing for Windows 11, enable it here. You may also need to set Secure Boot to "Standard" mode rather than "Custom".

Step 5: Save and Exit

Press F10 (or whatever your board uses to save) and confirm. Your system will reboot.

What Can Go Wrong — and How to Avoid It 🛑

Disabling CSM isn't universally safe for every setup. Here are the key variables:

Disk partition style matters. If your current Windows installation is on an MBR-partitioned drive, disabling CSM will likely break your boot. You'd need to convert the disk to GPT first using tools like mbr2gpt (built into Windows 10/11) before making this change.

Older graphics cards may stop displaying output. GPUs manufactured before roughly 2012 may not have UEFI GOP support, meaning they won't produce a signal in pure UEFI mode. If your screen goes black after disabling CSM, this is often why.

Some older peripherals or RAID configurations rely on legacy option ROMs that only work when CSM is active. Disabling it can break these configurations silently.

OEM machines (HP, Dell, Lenovo) sometimes handle this differently than DIY motherboards. On pre-built systems, CSM may be hidden, labeled differently, or tied to other security settings like TPM or BIOS passwords.

The Variables That Determine Your Outcome

Whether disabling CSM is straightforward or complicated depends on several factors specific to your machine:

• Age of your hardware — systems built before 2013 are more likely to have components that depend on CSM
• Current OS installation type — an MBR Windows install versus a GPT install changes your path significantly
• Motherboard manufacturer and BIOS version — interface layout and available options vary widely
• Discrete GPU model — older cards without UEFI GOP support behave unpredictably in pure UEFI mode
• Whether you dual-boot — a dual-boot setup with an older Linux distro or Windows version adds complexity

Some users disable CSM with two clicks and never look back. Others discover their system won't post, or Windows won't boot, and need to do preparation work first. The right path depends entirely on what's already running on your machine.