Why is a supported processor required for a BIOS update?

I know that this has happen to many of you: you finish building your new PC and it won't post.

It turns out that the older BIOS on the motherboard doesn't support your processor.

Unfortunately, you need a supported processor to update the BIOS.

This leads to a question

Why does the motherboard requires a supported processor (or even a processor at all) to perform a BIOS update?

It should be able to perform BIOS updates without even a processor installed.

While I'm not 100% sure why this is the case (probably something to do with not having the microcode to initialize a CPU properly), I can say that it's possible to flash almost any BIOS chip directly without the board itself. Procedures (and sometimes hardware) vary, but you can use something like a SPI programmer/interface, like this one: https://www.amazon.com/Signstek-Universal-MiniPro-Programmer-Interface/dp/B00K756PB6

Raspberry Pi's also have a SPI interface, which you can use to do something similar. It required a little extra hardware and tinkering, but I managed to use a Raspberry Pi to re-flash a BIOS chip on an old Gigabyte board that had a corrupted flash. You can do something similar in a case where your current BIOS doesn't support your CPU.

Some boards can flash with just a thumbdrive (usually fat32 with exact file name pattern in root dir) and no cpu or ram installed. They probably have to set up the bmc/me image to do this though, sadly this is not standard.

I suspect that it's because it would require extra hardware to provide any sort of user interface to do the flashing, which would make the board cost extra, and that doesn't make sense for anything but the most expensive enthusiast kinds of boards like that one that Asus sells specifically for overclocking.

With the little DOS or command line applications they typically use, they can use the regular hardware the board already has to read the image file off the disk and control the process of writing it to the BIOS chip. Without that, they have to implement some other hardware mechanism for that.

_mockingbird said:

I know that this has happen to many of you: you finish building your new PC and it won't post.

It turns out that the older BIOS on the motherboard doesn't support your processor.

Unfortunately, you need a supported processor to update the BIOS.

This leads to a question

Why does the motherboard requires a supported processor (or even a processor at all) to perform a BIOS update?

It should be able to perform BIOS updates without even a processor installed.

Click to expand...

The motherboard requires a supported processor to update the BIOS because the motherboard can't initialize the processor correctly without it. This can be due to issues including but not limited to CPU microcode, integrated voltage regulator support, voltage input, and other factors not being compatible. The BIOS flashing process requires a bootable environment to work from. That's just how the software side of it is designed.

Emission said:

While I'm not 100% sure why this is the case (probably something to do with not having the microcode to initialize a CPU properly), I can say that it's possible to flash almost any BIOS chip directly without the board itself. Procedures (and sometimes hardware) vary, but you can use something like a SPI programmer/interface, like this one: https://www.amazon.com/Signstek-Universal-MiniPro-Programmer-Interface/dp/B00K756PB6

Raspberry Pi's also have a SPI interface, which you can use to do something similar. It required a little extra hardware and tinkering, but I managed to use a Raspberry Pi to re-flash a BIOS chip on an old Gigabyte board that had a corrupted flash. You can do something similar in a case where your current BIOS doesn't support your CPU.

Click to expand...

The problem is that no one aside from ASUS and ASRock has removable BIOS ROM chips. Everyone else has them soldered onto the PCB. I'm not sure about updates to the BIOS without pulling the actual ROM unless the motherboard supports it. Extra hardware is required to make that work.

Aluminum said:

Some boards can flash with just a thumbdrive (usually fat32 with exact file name pattern in root dir) and no cpu or ram installed. They probably have to set up the bmc/me image to do this though, sadly this is not standard.

Click to expand...

Most of the major brands have gone to this or at least offer the feature on many of their models. ASUS has been doing this for YEARS. As has ASRock. GIGABYTE and MSI only recently added this functionality. ASRock's even have a BIOS update / resume on power loss feature. You can pull the power cord on the system during a flash and pickup where you left off. Blind flashing has been a thing since about 1996 on some motherboards. Intel's exquisite PR440FX Providence motherboard was capable of this.

RazorWind said:

I suspect that it's because it would require extra hardware to provide any sort of user interface to do the flashing, which would make the board cost extra, and that doesn't make sense for anything but the most expensive enthusiast kinds of boards like that one that Asus sells specifically for overclocking.

With the little DOS or command line applications they typically use, they can use the regular hardware the board already has to read the image file off the disk and control the process of writing it to the BIOS chip. Without that, they have to implement some other hardware mechanism for that.

Click to expand...

You are correct in that it does require special IC's which allow the system to operate in some form without the presence of a CPU or memory. However, you don't get video or an interface to work with. Sometimes the BIOS ROM image file is modified to work with this method. Essentially, it's another blind flash technique. Again this feature isn't new, it's just become more widespread in recent years.

Dan_D said:

The problem is that no one aside from ASUS and ASRock has removable BIOS ROM chips. Everyone else has them soldered onto the PCB. I'm not sure about updates to the BIOS without pulling the actual ROM unless the motherboard supports it. Extra hardware is required to make that work.

Click to expand...

I recovered a Gigabyte J1900N-D3V without de-soldering the BIOS chip. I had to provide my own power directly to the chip, and use a logic-level shifter so the Pi could communicate with the 1.8v chip correctly. You can use a SOIC8 clip to attach to it, or solder to it directly. I spent something like $20 for the logic-level shifter and the adjustable voltage regulator that I used to make a 1.8v supply, and then whatever the Pi costs. You can use a Pi Zero which is also quite cheap.

I've read on some forums that certain systems (laptops in particular) might have additional hardware around the chip that could interfere with the process, in which case a de-solder might be required.

Emission said:

I recovered a Gigabyte J1900N-D3V without de-soldering the BIOS chip. I had to provide my own power directly to the chip, and use a logic-level shifter so the Pi could communicate with the 1.8v chip correctly. You can use a SOIC8 clip to attach to it, or solder to it directly. I spent something like $20 for the logic-level shifter and the adjustable voltage regulator that I used to make a 1.8v supply, and then whatever the Pi costs. You can use a Pi Zero which is also quite cheap.

I've read on some forums that certain systems (laptops in particular) might have additional hardware around the chip that could interfere with the process, in which case a de-solder might be required.

Click to expand...

OK, makes sense. I've never seen that done before, as it isn't really needed on modern motherboards but it's nice to know that its possible.

The BIOS is nothing more than a software image stored on a flash chip that contains all of the instructions and settings the system needs to get itself up and running. The system is set so when the power is turned on or reset, that BIOS image is mapped into the address space that the CPU is hard-coded to start executing instructions from after powering on or resetting. The first thing the BIOS does is set the CPU and RAM up to be able to execute more complex code. Without being able to do that, the CPU can't find, load, and execute the necessary pieces of code that access a file system, open a file, and perform an erase and write cycle on the very chip that it's running out of until main memory is set up.

The motherboards that can flash a new BIOS without a CPU or RAM actually have a very basic CPU and a small amount of RAM built into the support chips that is pre-programmed to do all of those things without having to rely on a BIOS-image to tell it what to do.

Dan_D said:

OK, makes sense. I've never seen that done before, as it isn't really needed on modern motherboards but it's nice to know that its possible.

Click to expand...

The BIOS was corrupted to a point where it would freeze during POST, and I couldn't get the board to trigger the recovery BIOS, so using the board itself to do a re-flash was out of the question. It's been a while since I touched the board, but if I had to guess, I originally attempted to flash the BIOS with a later one, and it failed in some way, leaving me with a useless board.