Windows 10 boot camp on Mac Mini early 2009

This says no.

Use Windows 10 on your Mac with Boot Camp - Apple Support

This says no to Win 8.1 too

Use Windows 8.1 on your Mac with Boot Camp - Apple Support

This says you can run the 32 bit Win 7

Install Windows 7 and earlier on your Mac using Boot Camp - Apple Support

Yes, it appears that some users have successfully updated 7>10 on Mac which do not support 10.

My concern is that the Apple does says you have to use 32 bit 7 and that may complicate things. I would post here:

https://discussions.apple.com/community/windows_software/boot_camp

It is possible to update from W7 32-bit to W10 32-bit, but on the 2009 Mini, driver issues are the most likely problem. You can stay with drivers that W10 will provide, but some of your Apple-specific functions may not work as you want them.

I have managed to do it.

Unfortunately, the way to do it was slightly tortuous, reflecting the history of my Mac. And with the free W10 offer expired, the information may be less useful now...

I had installed Windows 7 32 bit with bootcamp on my Mac Mini 3,1 (aka early 2009), as back then I did not have too much RAM, only 2GB, and supposed 32 bit would work better with that memory. Afterwards, I upgraded to 8GB (and an SSD for good measure), but never got to upgrade W7 to 64 bit, as that needed a reinstall. When upgrading to W10, I decided that I'd like to move to 64bits... but that also needs a clean reinstall. So I procrastinated and did nothing for a while.

After the Microsoft e-mails of "29th of July is the last day of the free upgrade offer", I backed up all relevant files, and hoped for the best.

I did have to use the W10 upgrade program (the notification did not seem to work well) when running W7 on the MacMini, and after making space (15GB are needed) and selecting Windows as the BootCamp default booting system (for the reboots), everything went smoothly: all the programs were there, all the drivers and I had a 32bit W10 working. And a W10 license that I could use to reinstall.

I did go through the 32 bit W10 because I did not know how would I be able to get a W10 license if I reinstalled from scratch, but maybe I could have done it in just one step… who knows.

After that, I went through the motions to get the 64bit version of W10, which is slightly more involved, as some few things are not supported.

I started by downloading the W10 Media Creation Tool, and creating an USB drive with Windows 10 64 bit in my language.

After that, I booted on Mac OS X Yosemite (maybe el Capitán is better for this, I don’t know) and went through the BootCamp assistant to download the latest support drivers for Windows (that downloads the W7 version in a MacMini3,1) and install them in the USB.

Unfortunately, the created USB is not able to boot successfully, so I went back to W10 and the media Creation tool and created a DVD with the W10 media. This time, the Mac was able to boot successfully into the W10 installer and then I was able to install W10 64 bit, with a default VGA screen, not pretty to see… So I plugged the USB created with the W7 support, clicked on the \WindowsSupport\setup.exe, and it completely did nothing. But then a W10 popup recommended to restart the program with compatibility options and with that, the driver installation started. It got hanged in the installation of the SimgaTel audio driver, but I was able to keep on progressing by killing that installer only and let the program go.

After that, I got a working screen drivers, but, as suspected, the audio was not working. Doing some research online, it turns out that the MacMini3,1 does have a RealTek audio Chipset not a Sigmatel, so i tried to install the Realtek drivers and there it was: my full W10 installation on a Mac Mini (early 2009).

It’s probably too early to know all the things that do not work, but for now, Video, networking, audio, USB and the printers do work ok.

The only thing that has resisted me, is that I have not been able to create a W10 installation DVD with the added BootCamp WindowSupport directory that is usable to boot...😟 you can't have everything😉

Driver issues are the most likely problems as you continue experimentation.

Sooo I have been investigating this for a couple of weeks now, and here are the results and conclusions that I have come to:

I wanted to install a bare metal version of Windows 10 on a late 2009 Mac Mini that a friend recently gave me. I did not want to run Bootcamp. Just good ole' Windows. When I did an initial install from a Windows 10 creation tool listed HERE: https://www.microsoft.com/en-us/software-download/windows10 I was able to get 10 installed, but it kept trying to install a video driver update for the Nvidia Geforce 9400 automatically, and created a boot loop upon reboot. I was unable to recover at all through any methods. Hrmm. So I then reformatted and installed again, and turned off automatic updates, then ran a reboot. Success in blocking the updated driver install, but generic Windows driver now. So I attempted using the GeForce site's recognition tool as well as downloading several drivers through their site, all with the same results as before. I THEN attempted to use Nvidia drivers listed in Bootcamp to no avail as well. Further research brought me to this forum page, and upon learning that Apple indicated that this hardware is not supported for Windows 10, I decided to take it as a personal challenge.

Keep in mind each of these attempts involved reformatting the drive through a separate drive reader, quite annoying. My next attempt was to install Windows 7. First through a bootable USB drive, no go. I was then able to get a Windows 7 Professional install on the drive from an install through external optical drive (the on board one was hosed hardware wise). SUCCESS! Sort of. Unable to run Windows updates. GAH. I THEN got one of the earlier Bootcamp zip files to support Windows 7, unpacked it. I was able to update manually through device manager, both the video adapter and the weird co-processor error that you will see cleared out. Several other items updated through Device Manager, make sure to go through and test them all.

Still no good on Windows Update. Tried running Windows Update fix utility from online, found some problems, fixed them. Windows Update still won't run. Sigh. NEXT. Back to the Windows 10 installation tool from URL mentioned above. Tried running it and letting the tool run Windows updates during install, updated just times out like the one built into Windows 7. Longer sigh. Re-start the installation process, do not select to run updates during installation. WINDOWS 10 SUCCESS!!! Almost. Co-processor error still gone, video adapter still sees the Geforce adapter, but with an exclamation mark. Sighz. Check the message, asking for a reboot. Reboot the box, full resolution showing, ERROR GONE!!!!

Currently installing updates, which are finally working, crossing fingers. My initial gut feeling that this hardware should be able to support Windows 10 bare metal was correct. Hoping this information helps some folks out there from jumping through all the hoops I did, good luck.