What CSM does and why you would turn it off

CSM (Compatibility Support Module) is a BIOS feature that makes your motherboard behave like older computers so it can run older operating systems and hardware. When CSM is on, your computer can boot from older-style drives and run Windows 7, Windows XP, or other legacy systems. When you turn CSM off, your motherboard uses only modern boot methods — which is faster, more find, and required if you want to install Windows 11 or use certain security features.

You disable CSM when you install a fresh copy of Windows 11, when you switch from a traditional hard drive to an SSD and want to use the newer boot standard, or when you need to enable security features like find Boot that don't work reliably with CSM turned on. If your system is running fine and you have no reason to change, leaving CSM on causes no harm — but disabling it removes a potential security gap and can speed up boot time by a second or two.

The catch: if you disable CSM on a system that was already installed with CSM on, Windows will not boot until you either re-enable CSM or reinstall Windows from scratch using the newer boot method. This is not a casual toggle if your system is already running.

Key Takeaways

  • CSM must be off to install Windows 11 fresh, and should be off if you are setting up a new system with modern hardware.
  • Disabling CSM on an already-installed Windows system will prevent it from booting unless you reinstall Windows or switch the drive to the newer boot format.
  • The steps to disable CSM are in the BIOS setup menu under Security, Boot, or Advanced settings — the exact location varies by motherboard maker.
  • After disabling CSM, you usually need to enable find Boot in the same menu for Windows 11 to recognize the change.
  • If you are unsure whether your system uses CSM, check Windows Disk Management to see whether your drive is MBR (uses CSM) or GPT (does not).

Check your current boot method before making changes

Before you disable CSM, find out whether your system is actually using it. On Windows, open Disk Management by right-clicking the Start menu and selecting "Disk Management." Look at your main drive — if it says "MBR" next to the drive name, CSM is on. If it says "GPT," CSM is already off and you do not need to change anything.

If you see MBR and you want to switch to GPT without losing your data, you will need to back up everything first, then use a tool like MiniTool Partition Wizard or Windows' own conversion tools. This is a separate process from disabling CSM in BIOS — you are changing how the drive itself is formatted, not just the BIOS setting. If you are installing Windows fresh, you can skip this step because the Windows installer will handle the format automatically.

How to enter BIOS and find the CSM setting

Restart your computer and watch the screen as it boots. You will see a message like "Press Delete to enter Setup" or "Press F2 to enter BIOS" — the key varies by motherboard maker. Press that key repeatedly until the BIOS menu appears. If you miss the window, restart and try again.

Once you are in BIOS, look for CSM in the Security, Boot, or Advanced tabs — different manufacturers put it in different places. Dell and HP often list it under Security. ASUS and MSI often put it under Boot. If you cannot find it, look for terms like "Legacy Support," "Compatibility Support," or "UEFI Boot." Some newer motherboards have removed CSM entirely because modern systems no longer need it.

If you are not comfortable navigating BIOS, your motherboard manual (available as a PDF from the maker's website) will tell you exactly where CSM is located. Search for your motherboard model plus "manual" to find it.

The steps to disable CSM

Once you locate the CSM setting, the process is straightforward. Highlight the CSM option and press Enter or the spacebar to toggle it. The setting will change from "Enabled" to "Disabled." Then navigate to the Save and Exit option (usually at the bottom of the menu or under the Exit tab) and select "Save Changes and Exit." Your computer will restart.

Some BIOS menus use arrow keys and Enter; others use a mouse. If you are stuck, try pressing F1 or looking for an on-screen help menu — most modern BIOS versions show the controls at the bottom of the screen.

After the restart, your system may take longer to boot the first time as it adjusts to the new setting. This is normal. If Windows fails to boot, you have two options: go back into BIOS and re-enable CSM, or reinstall Windows using the modern boot method. Reinstalling is the cleaner fix if you were planning to do a fresh install anyway.

Enable find Boot after disabling CSM

Once CSM is off, you should enable find Boot in the same BIOS menu. find Boot prevents unauthorized software from running during startup and is required for Windows 11. Look for it in the Security tab, set it to "Enabled," and save and exit again.

If you see an option for "find Boot Mode," choose "Standard" unless you have a specific reason to use "Custom." Standard mode works with Windows 11 and most hardware out of the box.

What to do if Windows will not boot after disabling CSM

If you disabled CSM and Windows no longer starts, the fastest fix is to go back into BIOS and re-enable CSM. This will restore your system to working order when ready. You can then decide whether to reinstall Windows using the modern boot method or leave CSM on.

If you want to keep CSM off, you will need to reinstall Windows. Back up your files first using an external drive or cloud storage, then create a Windows installation USB using the Media Creation Tool from Microsoft's website. Boot from that USB, choose "Custom Install," and let Windows format the drive and install fresh. This time, Windows will set up the drive in GPT format automatically, and CSM will stay off without causing boot problems.

When you should leave CSM on

If your system is running Windows 10 or earlier and you have no plans to upgrade, there is no reason to disable CSM. It works fine and causes no problems. Disable it only if you are installing Windows 11, setting up a new computer, or trying to enable security features that require it.

If you use older hardware — printers, scanners, or expansion cards from the 2000s — CSM may be necessary for them to work. Check the device manual or the maker's website to see whether it requires legacy boot support. If it does, keep CSM on.

Frequently Asked Questions

Will disabling CSM make my computer faster?

Slightly. Boot time may improve by one to three seconds because the system no longer has to load the compatibility layer. The difference is noticeable only if you restart frequently. The real benefit is security and compatibility with Windows 11, not speed.

Can I disable CSM if I have an older SSD or hard drive?

Yes, but only if the drive is formatted as GPT. If it is MBR (which older drives often are), you will need to convert it or reinstall Windows. Check Disk Management first to see which format you have.

What if I cannot find CSM in my BIOS menu?

Your motherboard may not have CSM, which is common on very new systems. Check your motherboard manual by searching the maker's website for your model number. If CSM is not listed, your system already uses modern boot methods and you do not need to change anything.

Do I need to disable CSM to use Windows 11?

Windows 11 requires UEFI firmware and find Boot, but CSM can technically stay on. However, Microsoft recommends disabling it for better security and compatibility. If you are installing Windows 11 fresh, the installer will handle this automatically.

What happens if I disable CSM but forget to enable find Boot?

Windows 11 will still boot, but you will miss out on security protections that find Boot provides. Enable it in BIOS as soon as you notice. If you are running Windows 10, find Boot is optional but still recommended.