Windows 10/11 on a 2009 Mac with GeForce 9400M

It is not difficult to install, but it is difficult to get brightness adjustment working, as shown in this YouTube video. We do not want it stuck at the maximum. If you follow some steps, brightness adjustment will work.
The trick is to use legacy mode instead of EFI mode. EFI mode is usually better, but not this time.

The setup process is explained in this video. This page is the written version.

A note about Windows 11 support

Needless to say, this machine does not support Windows 11 officially, so installing in legacy mode does not make things any less supported. Security updates will arrive, but they will end eventually. Security updates have already ended for Windows 11 version 21H2 and 22H2. If you have Windows 11 version 23H2, security updates end in November 2025, merely one month after Windows 10.
Newer Windows 11 feature updates that include more security updates, like 24H2 and so on, may not run at all because the kernel is updated to absolutely require a newer CPU from at least 2010.

In any case, if your computer does not meet the official Windows 11 requirements, you will have to install feature updates manually every year. If you have Windows 11 version 22H2 on an unsupported computer (not just a Mac), and it is fully updated with Windows Update, you can get this enablement package (x64 version) to update to version 23H2 (also shown in this short video).

Boot up the Windows 10/11 installer in legacy mode on a Mac

A Mac cannot directly boot up from USB flash drives in legacy mode. This means you need a CD or DVD for installation.
If your Mac's internal optical drive is removed or broken, you can use an external USB optical drive.

Download the ISO file for Windows 10 or Windows 11, then pick one of these two options:

Option 1: with a DVD only

  1. Burn the Windows ISO file to a dual-layer DVD R.
  2. Start up your Mac while holding down Alt or Option. Insert your burned DVD if you haven't already.
  3. Wait for your DVD to appear and then choose the "Windows" option. DO NOT choose "EFI Boot".

This option may not work with Windows 11 because the system requirements are not bypassed, but maybe you can bypass them from the Windows installer after it has started.

Option 2: with a CD and a flash drive

  1. Using Rufus on a Windows computer, write the Windows ISO file to a USB flash drive in MBR mode (with system requirements bypass if using Windows 11).
    Alternatively, you can copy the Windows ISO file to a flash drive set up with Ventoy, as long as it was set up with MBR partition style.
  2. Burn Plop Boot Manager to a CD or DVD (download Plop from this zip file, then extract and burn plpbt.iso. You don't need the other files).
  3. Start up your Mac while holding down Alt or Option. Plug in your flash drive and insert your Plop CD if you haven't already.
  4. Wait for your CD to appear and then choose the "Windows" option with CD icon. DO NOT choose "EFI Boot" or your flash drive.
  5. Plop will start and show a menu on the top left. Select USB.

If you're using a USB optical drive, unplug it before selecting USB. Only keep your flash drive plugged in once Plop has loaded.
If it gets stuck after selecting USB, restart and plug in your flash drive to a different USB port.

Installation

If the Windows boot screen and installer are not at your native display resolution (they look blurry and stretched), you've successfully booted up in legacy mode, so you can begin installation. If not (it looks nice and sharp), you're in EFI mode which is not correct in this case, so shut down and try again.

Install Windows as normal. Make sure you choose the right partition if dual-booting, or you will delete your other OS and data.

Post-installation

After installing the operating system you also have to install drivers and set up a few important things.
It is recommended to stay disconnected from the Internet while following the first four steps.

  1. Download the Boot Camp 4.0 Windows support software from the Boot Camp Assistant app on Mac OS (save it to a flash drive) or from Brigadier on a different Windows computer with Internet connection and command prompt. Example command for this Mac: brigadier --model MacBookPro5,4 (similar models use the same files).
  2. After downloading/extracting/copying the Windows support software to your Mac, right-click on the setup application and go to Properties (or click on it and press Alt+Enter or Option+Enter), and enable compatibility mode for Windows 7. Then install it.
    When it asks to restart, DO NOT RESTART.
  3. Go to the folder \Windows\System32\Drivers and replace MacHALDriver.sys with this newer version.
    Now you can restart.
    (If you accidentally restarted before replacing this file, you can boot from a live USB drive of a Linux distribution, even in EFI mode, to replace the file.)
  4. Update the GeForce 9400M drivers to the newest version, 342.01.
    (This installer is for other similar Nvidia GPUs too, see the Supported Products list)
  5. Open Regedit, go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E968-E325-11CE-BFC1-08002BE10318}\0000, create a DWORD 32-bit value called EnableBrightnessControl and set it to 1. (Or just download and install this registry key.) This registry edit will have NO effect if you installed Windows in EFI mode on this Mac.
    You may have to restart again.
  6. Download Macs Fan Control and set it up to speed up the fan based on the temperature of CPU Proximity or CPU Diode. A good setting is to start speeding up the fan past 40°C, max speed at 80°C. If you do not set up this app adequately, your CPU will run too hot and it could damage your computer.
    (It is also a good idea to use that program on Mac OS on any Intel Mac.)
  7. (Optional) If in Device Manager you see a device called "Coprocessor" with missing driver, you can get it from here: NVIDIA nForce System Management Controller. Extract it, right-click on oem35.inf and select Install.
  8. (Optional) You can get improved trackpad drivers to meet Windows Precision Touchpad specifications. Download the amd64 version, extract it, right-click on AmtPtpDevice.inf and select Install.

After installing any available Windows updates, your Windows installation on this older Mac should be ready to use.

If you are dual booting and the time keeps changing when switching between OSs, open Regedit, go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation, create a DWORD 32-bit value called RealTimeIsUniversal and set it to 1. (Or just download and install this registry key.) This can be used on any computer with Windows dual boot.

If the screen locks up, restart the video driver by pressing Shift+Ctrl+Cmd+B or Shift+Ctrl+Windows+B.

Sometimes the whole computer may lock up when waking up from sleep or hibernate mode, requiring a reset. I have not found a solution to this.
If you have any feedback, comment on my YouTube video.

TheComputerGuy96
Last updated on Oct 3, 2024