Flashing Your BIOS with No CPU Installed

Introduction

If you have a modern DIY desktop PC that uses a motherboard from one of the large motherboard vendors from Taiwan (such as ASUS, ASRock, Gigabyte, or MSI), there is a good chance that you can flash the BIOS with no CPU installed. This will only work if your motherboard supports this functionality.

Flashing Your BIOS with No CPU Installed
Flash BIOS Button

You might be wondering why you would ever need or want to do such a thing. Well, the most common scenario is if you are building a new system from parts. You might have a new CPU that is not supported on your motherboard without a BIOS update. The CPU is physically compatible with the motherboard, and it will work just fine after a BIOS update, but the system will not POST until you update the BIOS.

This is happening right now to many people who have bought a new AMD Ryzen 5000 Series processor, planning on using it with a new B550 or X570 motherboard. Even though the motherboard is brand new, it very likely is a month or two (or more) since it was actually manufactured.

That means that it will have whatever BIOS version that was most current when it was made. This means that it is usually not going to have the most current BIOS version, since there are typically multiple BIOS updates that are released in the first few months after the initial release.

I have never bought a new motherboard that had the latest BIOS version when I took it out of the box. Normally, this is not a huge issue, since it is usually pretty easy to update the BIOS if you want to. But, if you need a BIOS update before the system will POST, what are you supposed to do?

Different Ways to Correct the Problem

One way around this is to temporarily install an older, compatible CPU in your new motherboard. Then you can use a traditional method to update the BIOS to a new enough version that will support the newer CPU. Of course, this only works if you have an older compatible CPU available. Not everyone has that luxury.

Another method is to get the store where you bought the CPU and motherboard to flash the BIOS for you. This will probably work at somewhere like Micro Center, but it isn’t going to work with a mail order retailer (at least not that I know of).

In the past, AMD had a program where they would send you an inexpensive, low-end CPU that you could temporarily install so that you could flash your BIOS to a new enough version to support your new CPU. If you did not return the loaner CPU, they would charge you for it.

AMD has updated guidance about how to handle this issue. This includes several different methods for updating the BIOS, and includes a “Short-Term Processor Loan Boot Kit” that you can get. You will have to jump through some hoops to get it though.

Flashing Your BIOS with No CPU Installed

Now, most mid-range and above B550 and X570 motherboards have a feature that lets you flash the motherboard BIOS without even installing a CPU, memory, or a GPU. All you need is a power supply that is connected to the 24-pin main and 8-pin EPS power connectors on the motherboard.

You have to use another system to download a new BIOS file to a USB 2.0 flash drive, rename the file, and then plug it in to a designated USB port on the motherboard. Then, you press the Flash BIOS button, and wait a few minutes for the BIOS update to finish. This is a fairly simple procedure, with some important details that are sometimes missed.

So far, I have made three YouTube videos about how to do this with three different motherboards. All of these videos seem to be fairly popular so far.

How to Flash the MSI MPG B550 Gaming Edge WiFi BIOS with the Flash Back Button
How to Flash an MSI MAG B550 Tomahawk BIOS with No CPU
How to Flash the MSI MAG B550M Bazooka BIOS with the Flash BIOS Button

Another use case for this technique is if you have tried to flash your BIOS in the traditional manner, and the procedure failed. This is very rare, but also very bad, since it usually makes it so your system will no longer POST. This technique will often fix that issue, since it uses a completely separate method for flashing the BIOS.

Final Words

This is a common problem with AMD Ryzen 5000 Series CPUs in existing motherboards. This particular issue will be less common over time as newer production motherboards show up in the retail channel. Any B550 or X570 motherboard that was manufactured after late October 2020 should have a new enough BIOS version where you won’t have to worry about this.

Flashing Your BIOS with No CPU Installed
BIOS Updates for Ryzen 5000 Series

I also have some related posts here:

If you have any questions about this post, please ask me here in the comments or on Twitter. I am pretty active on Twitter as GlennAlanBerryThanks for reading!

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