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NOTE: The below mentioned procedures may no longer work. I intend to look into it and update this article at some point but this can take many months. Proceed if you want, it might work, it might fail. Check the comments for possible workarounds and solutions found by others.

Hanging out in the various Facebook groups and other communities, I rarely run into anyone anymore that has a 2009 4,1 Mac Pro that still runs the stock firmware. But there are many Mac Pro users that are not aware of those communities or of the upgrade potential and possibilities for their Macs. They don’t see this kind of information on a daily basis like this geek. I took this knowledge for granted, forgetting there’s a whole world of people out there that have no idea this knowledge exists.
If you are one of those people or know one of those people that have a 2009 4,1 Mac Pro and want to squeeze another decade of life out of it, this page is for you!

This topic has been covered in the past but all those guides appear outdated, have broken links, needlessly complicated processes, or a combination of all those. Therefore I’ve decided to write a clear, to the point, 2021 version with links to pieces of this puzzle still available from their original source, and pieces no longer available that are now hosted on this website. So you’ll have everything you need in one place.

Terminology (simplified):

4,1 Mac Pro – 4,1 refers to the Model Identifier of the 2009 Mac Pro, MacPro4,1
5,1 Mac Pro – 5,1 refers to the Model Identifier of the 2010 and 2012 Mac Pro, MacPro5,1
Firmware – Code on a chip that gives the machine the basics of how it needs to operate
SIP – System Integrity Protection. A feature introduced in Mac OS X 10.11 El Capitan that protects certain system components such as the firmware from being edited or tampered with
CPU – Short for Central Processing Unit, also known as the Processor
GPU – Short for Graphics Processing Unit, also known as the Graphics Card
Mac Flashed GPU – A graphics card that allows you to see the startup/boot screen on a Mac. This can be an Apple GPU that came with your Mac Pro, or an aftermarket GPU that had Mac firmware flashed to it.
Metal – A new to macOS graphics framework that is required to install and run macOS Mojave and newer. Not every GPU can support this new Metal framework. It replaced the older and slower OpenGL framework you may have heard of or be familiar with. If your 4,1 Mac Pro has the GPU that came with the machine, you can be sure it is not Metal capable.

How:

The 4,1 and 5,1 Mac Pro are 99.9% identical. The only major difference being the kind of processors they take in a dual-processor setup. So, giving the logic board of the 4,1 the firmware of the 5,1 allows you to do everything a real 5,1 Mac Pro can do.

Why:

Having your 4,1 Mac Pro think it’s a 5,1 Mac Pro, allows you to upgrade the OS past 10.11 El Capitan. 10.12 Sierra, 10.13 High Sierra and 10.14 Mojave will all install natively without further patching or other trickery. You will also be able to replace the 4-core processor with a 6-core processor. Or two if you have a dual-processor model. This can get your Mac Pro up to one or two Intel Xeon X5690 6-core 3.46GHz chips which is a major boost in performance. 3.06GHz and 3.33GHz processors are also options.
With faster processors come more perks than just a raw speed increase. The system bus will operate faster, the amount of cache goes up and last but not least; your Mac will be able to use faster RAM. The 4,1 Mac Pro uses 1066MHz RAM, the 5,1 Mac Pro uses 1333MHz RAM. Now that your 4,1 thinks it’s a 5,1 and with a newer processor, it can utilize the 1333MHz RAM as well, adding to the performance increase.

Prerequisites:

• A 2009 (4,1) Mac Pro.
• A Mac or Mac flashed graphics card (GPU) is required.
• You must run Mac OS X 10.9 Mavericks or newer.
• The Firmware Tool (now links to a locally hosted file since Netkas is down)
• The firmware disk images (4,1 and 5,1 firmware disk images in one zip file)

Steps:

1. Make sure your Mac is connected to the internet.
   The Firmware Tool initially needed an internet connection to download the firmware files from Apple’s website. However, the links the Tool used to get those files stopped working long ago. Even though the Firmware Tool can’t download these files anymore, it will still require an internet connection or it will error out and quit. In 2017 someone fixed the links the Tool used to download those files but they broke again shortly after. This is why I just host these files on my own server now.
2. Disable SIP (If you run Mac OS X 10.11 El Capitan)
   • Boot to your recovery drive or from an installer drive
   • Open the Terminal app
   • Type “csrutil disable” without the quotes
   • Hit the Enter key
   • A message will confirm System Integrity Protection is now disabled
   • Restart your Mac
3. Open the FirmwareFiles.zip and open MacProEFIUpdate1-5.dmg to mount the disk images on your desktop (don’t install the package it contains)
4. Run the Firmware Tool
   • Read all of the information the Tool provides
   • Click the “Upgrade to 2010 Firmware” button
   
5. Follow the instructions when the flashing is done
   • Shut down the Mac
   • Press and hold the power button until it starts to rapidly blink, then let go
   • A loud tone will follow
6. The optical drive ejecting confirms the detected firmware is valid and the update will begin
   • A thick empty progress bar will slowly fill up as the firmware is updated
   • The Mac will restart once the update has been completed
7. Your Mac is now, for all intents and purposes, a 5,1 Mac Pro. The firmware at this point should be “MP51.007F.B03”.
   • Go to the Apple menu > About This Mac > System Report
   
8. (optional) Boot to your recovery partition or a flash drive installer and re-enable SIP if you want.
   • Same process as disabling it, only this time type “csrutil enable”, without quotes, in the terminal

Can this be reversed?

Yes, using the same files you can downgrade the firmware back to that of a 2009 4,1 Mac Pro. Keep in mind that you’d also have to put the quad-core processor back in. Downgrade the operating system to 10.11 El Capitan. And the 1333MHz RAM you may have installed may experience some weird quirks. The RAM *should* down clock it’s speed to 1066MHz but this is hit or miss depending on the brand and capacity of the RAM modules.
I suggest you save the FirmwareFiles.zip and the Firmware Tool app. If for whatever reason you want to downgrade your Mac Pro back to the original firmware, the same tool and files are needed. That said, I have yet to see a good reason to downgrade the firmware.

Which processor(s) should I pick?

I’m a big fan of the 6-core X5675 3.06GHz processors. They run fast, use a lot less power than their 3.33 or 3.46GHz alternatives, and inside a Mac Pro pretty much always run at their turbo boost speed of 3.46GHz. Also a pair of these averages $50 on eBay. It all depends on what you use the Mac for. I recommend taking a look at the Definitive Classic Mac Pro Upgrade Guide to see which processors are available to pick from, then pick one accordingly. Once you’re all done and enjoying a Faster and better Mac Pro, go back to the guide I just linked to and read all of it. You’ll learn a ton and might get other good ideas on how to further improve your Mac!

Is there more that can be done?

Since you asked, yes there is! Your Mac is already identifying as a 5,1 and there are more firmware updates you can now do. If you’re running Mac OS 10.11 El Capitan or 10.12 Sierra, you can use the 10.13 High Sierra installer to get firmware “MP51.0089.B00” which brings APFS support and several security bug fixes to the microcode. If you have a GPU that is Metal capable, you can use the Mojave installer to get firmware version “144.0.0.0.0” which brings all improvements from previous firmwares along with NVME SSD boot support and other enhancements.
These firmware updates are part of the OS installers but they are separate steps. So you can run the installer, do the required firmware upgrade, then quit the installer. This allows you to use the latest firmware without having to run that particular operating system. Unless you want to, of course.

Your Mac Pro must have a Metal capable graphics card installed if you want to use the Mojave installer firmware. And due to Apple’s refusal to allow certain GPU drivers, not all Metal capable GPU’s work on Mojave. So do your research before picking a metal-capable card for your Mac. If you do not have a Metal capable graphics card, follow the steps below but use the High Sierra installer instead. This will still give you newer firmware which can’t hurt to have.

Steps:

1. Download the latest High Sierra/Mojave installer
   • You can get High Sierra here
   • Or you can get Mojave here
2. Run the installer, select a language if it asks for it
3. You’ll see a window stating a firmware update is required to install macOS High Sierra/Mojave, along with instructions on how to do this update
4. Follow the instructions and do the update
   The firmware update will install and the Mac will restart. The optical drive ejecting confirms the detected firmware is valid
   If the macOS installer pops up again after the restart, just quit out of it (or continue the OS install if you want), the firmware is all we were after in this case.
5. The firmware at this point should be “MP51.0089.B00” if you ran the High Sierra installer and “144.0.0.0.0” If you ran the Mojave installer
   • Here is the same Mac displayed in an earlier screenshot, now with a 6-Core CPU and the Mojave firmware
   

No need to try this with macOS 10.15 Catalina or 11.1 Big Sur. These operating systems are not natively supported by the 5,1 Mac Pro so no new firmware was made for these machines. The Mojave firmware is as good as it gets. But hey, that’s firmware several years newer than the one you were running before!

You can get macOS Catalina or Big Sur installed on your Mac Pro, quite easily too but I’ll get into that some other time. Just know those operating systems won’t offer any firmware benefits.

I hope this to-the-point guide was helpful. Let me know in the comments any feedback you may have!