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, BIOSTAR, Gigabyte, or MSI), there is a good chance that you can flash the BIOS with no CPU installed. This post is about Flashing Your BIOS with No CPU Installed.

Note: 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. This is also happening to people who have bought new Ryzen 5000 APUs, such as the Ryzen 5 5600G and the Ryzen 7 5700G. Most B550 and X570 motherboards will need an updated BIOS to work with these APUs.

Even though the motherboard is brand new in the box, it very likely is a month or two (or more) since it was actually manufactured in Taiwan.

That means that the motherboard 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 now 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 back of the motherboard. Then, you press the Flash BIOS button, and wait for five to six minutes for the BIOS update to finish. This is a fairly simple procedure, with some important minor details that are sometimes missed.

So far, I have made nine YouTube videos about how to do this with nine different motherboards. All of these videos seem to be fairly popular. They are far more popular than any of my SQL Server videos!

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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.

BIOS Flashing FAQ and Troubleshooting

Frequently Asked Questions

  • Will this method work on a fully-assembled system?
    • Yes, it will. Make sure to not turn on the system with the power button on the case. Just press the flash BIOS button. Your CPU and case fans will probably turn on while this is happening.
  • Does this method work with no CPU, RAM, video card, or monitor attached?
    • Yes! That is the whole point of this method.
  • Do I need to use this method if I have a Ryzen 3000 Series CPU?
    • No, you don’t. You can still use this method, but you don’t have to. This method is mainly for flashing the BIOS when you have a new CPU that won’t work with the current BIOS version
  • Can I do this with the motherboard sitting on top of the motherboard box instead of on a test bench or in a case?
    • Yes, you can do that. You just need to make sure the motherboard is not sitting on anything that conducts electricity.
  • Is the BIOS flash process done when the flash BIOS LED stops blinking?
    • Yes it is. It should have blinked for 5-6 minutes. If it only blinked for a few seconds, it did not work.
  • The BIOS flash LED has been flashing for a long time (far longer than 5 minutes). What should I do?
    • It should not take more than 5-6 minutes. If you have waited more than 10-15 minutes and it is still flashing, it is not working. At some point, you have to give up and turn the power supply off or unplug it. If this happened to you, I would try using a different USB drive, and make sure to follow all of the steps exactly.

Troubleshooting Steps

Here are some general troubleshooting steps for MSI motherboards in case you have any issues:

  • Did you watch the entire video, and follow the directions exactly?
  • Are you using a USB 2.0 flash drive instead of a USB 3.0 flash drive?
  • Did you download the latest BIOS file for your motherboard?
    • Make sure you don’t have a BIOS file for a different motherboard
  • Do you have file extensions enabled in Windows Explorer?
    • This way the BIOS file will actually be renamed correctly
  • Did you rename the BIOS file as MSI.ROM (for MSI motherboards)?
    • This is very important!
  • Did you rename the BIOS file as gigabyte.bin (for Gigabyte motherboards)?
    • This is very important!
  • Is the USB flash drive formatted with FAT32 rather than NTFS or exFAT?
    • This is very important!
  • Make sure the USB flash drive is partitioned with MBR instead of GPT
  • Is the renamed BIOS file in the root of the USB flash drive?
    • It cannot be in a folder or directory
  • Are both power supply cables (24-pin main and 8-pin EPS) plugged into the motherboard?
  • Is the USB flash drive in the correct USB port (the one with the white outline)?
  • Did you plug in the USB flash drive before you turned the power supply on?
  • Is the power supply plugged into a power source?
  • Did you just press the Flash BIOS button (rather than turning the system on normally)
    • You do not want to turn the system in the normal fashion for this
  • Did the BIOS flash LED on the motherboard flash for 5-6 minutes, and then stop flashing?
    • If it only flashed for a few seconds, it did not work!

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!

7 thoughts on “Flashing Your BIOS with No CPU Installed

  1. In Troubleshooting Steps you can add point to make sure that USB flash drive has MBR partition s not GPT. I saw few cases where that was problem.

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