Question Does flashing a B450 make it incompatible with older CPUs?

[Mawla]

I read somewhere that, once you flash a B450 motherboard to make it compatible with a 5000 series CPU/APU, there's no going back (the actual words) and the motherboard will no longer support older processors. Is this true?

 

[Colif]

It can be the case with some Asrock boards in that flashing it to support newer removes support for say Pinnacle Ridge CPU.

for instance:

ASRock do NOT recommend updating this BIOS if you are going to use Pinnacle, Raven or Summit Ridge CPU on your system.

https://www.asrock.com/mb/amd/b450m steel legend/#BIOS1

its not all makers, MSI doesn't seem to remove support:
https://www.msi.com/Motherboard/B450-TOMAHAWK-MAX/support
Gigabyte don't - https://www.gigabyte.com/au/Motherboard/B450-AORUS-ELITE-rev-1x/support#support-dl-bios
Asus don't appear to either - https://rog.asus.com/motherboards/rog-strix/rog-strix-b450-f-gaming-ii-model/helpdesk_bios/

So it can depend, you need to look at the board to see what the BIOS updates say.

 

[Mawla]

Thanks. I'll do some more reading and come back with more questions if necessary.

 

[Colif]

They removed it as some BIOS don't have the space required to keep the additional settings, so by supporting new they have to drop old.
It seems to mostly be Asrock who dropped support. They may not have as much space on the BIOS chip to save everything.

 

[Mawla]

Does it mean that, even with motherboards that have provision to restore the old BIOS version (such as those with a flashback button), they will no longer support older cores without a flashback?

To put it another way, can the new BIOS version support say, both Cezanne and Picasso processors? Or does it depend on what the manufacturer did for a particular model?

 

[Colif]

Does it mean that, even with motherboards that have provision to restore the old BIOS version (such as those with a flashback button), they will no longer support older cores without a flashback?

Yes. If the update removes the support for the CPU, you have to rollback to before it to get full support.

That asrock has a BIOS update number 2.50 that you cannot rollback past.

User will not able to flash previous BIOS once upgrading to this BIOS version.

So its a double whammy. You can't go back past 2.50 and if you have Pinnacle Ridge, you shouldn't go forward past it either. 2.50 is as far as they go.

But really, most people only update BIOS on older PC if they are having problems. I don't even update my new board if its working fine. I am about 6 bios versions behind.

To put it another way, can the new BIOS version support say, both Cezanne and Picasso processors? Or does it depend on what the manufacturer did for a particular model?

i would have to look at every board but it seems it mostly depends on if board is made by Asrock. The other big MB makers seem to just add features and rarely remove them.

 

[drea.drechsler]

I read somewhere that, once you flash a B450 motherboard to make it compatible with a 5000 series CPU/APU, there's no going back (the actual words) and the motherboard will no longer support older processors. Is this true?

I can confirm it does with the MSI's non-MAX B450 boards; I've got a B450m Mortar.

The first processors that were dropped are the Bristol Ridge APU's, no big loss from AM4 since they're not even built on Zen architecture of any generation. The next processors that can't work are first gen CPU's (1000 series), I'm not sure of 2nd gen CPU's (2000 series) or 2000 series APU's.

Does it mean that, even with motherboards that have provision to restore the old BIOS version (such as those with a flashback button), they will no longer support older cores without a flashback?

To put it another way, can the new BIOS version support say, both Cezanne and Picasso processors? Or does it depend on what the manufacturer did for a particular model?

This depends on how the motherboard mfr is handling reversions. Many don't allow reverting to older BIOS's once updated, many only do so for certain rev. levels. I upgraded my B450 Mortar from a 1700 to a 3700X before I got my B550 board. After moving I couldn't roll back to a BIOS to support the 1700 again because MSI had imposed a reversion block.

The B450m Mortar has a bios flashback but it would not do the reversion either using that or the in-BIOS updater, M-Flash. But I was able to do the reversion using a command line BIOS flash tool and using command line option to ignore version and validity checking.

A BIOS can support a particular CPU/APU based on the SMU blocks that are included in the BIOS. So use a tool called "SMU Checker" to check BIOS's to see which Zen architecture variants (Summit Ridge, Cezanne, Matisse, Bristol Ridge, etc.) are supported.

 

[Mawla]

Thanks again for the replies. I have two reasons for asking these questions: One is academic interest and the other is that I sometimes use my home office computer as a test bench. I'm going to order parts for a new system based on the Ryzen 7 5700G and would like to retain compatibility with at least some older processors if that's possible.

 

[drea.drechsler]

Thanks again for the replies. I have two reasons for asking these questions: One is academic interest and the other is that I sometimes use my home office computer as a test bench. I'm going to order parts for a new system based on the Ryzen 7 5700G and would like to retain compatibility with at least some older processors if that's possible.

To be certain you can run a specific AM4 processor on the latest BIOS it's a good idea to get the SMU Checker utility. Your mfr. may have blocked reverting to a pre-Win11 compatible BIOS without resorting to a command line flash tool.

You'll almost certainly not be able to run Bristol Ridge though. Not a big loss.