Will Ryzen 4th Gen be hindered by backwards compatibility with 3rd Gen motherboards?


This is something I’ve been pondering for a while. Where AMD were originally going to end the backwards compatibility a generation early but have since reverted their stance on it. Do you think that this will hamper the abilities of Ryzen 4000 for the desktop in order to allow for earlier generations to still be able to use the new chips? If so, could the full potential of Zen 3 not be realised until we see a Ryzen 5000 series chipset?

If we’re to believe AMD’s stance, which is corroborated by mainboard manufacturers, not at all. There’ll be artificial limitations in place, with older chipsets not supporting PCI-e gen 4, even though they’ve been shown capable, but that shouldn’t limit CPU performance in any way.

As far as we know, the 4000 series will be the last chips to use the AM4 socket. Zen 4 chips will probably use DDR5 memory - rendering AM4 socket boards unusable, but their release won’t be for at least another two years.


That kind of begs the question of what the point of making it backwards compatible in the first place was then, don’t you think? Obviously the marketing of not sticking to what they said is bad, which is how it ended up playing out, but you could argue that they didn’t think it was worth supporting based on just how significant the limitations effect the performance of the actual chip. I guess we’ll have to wait and see just how significant the difference between older and newer chipset performance is.

There’s a limitation due to BIOS memory size with 400 series boards and below, which meant they couldn’t support older CPUs/APUs and the new ones in the same BIOS. Vendors have come out with multiple BIOS versions to address this issue, mainly dropping support for Zen 1 chips.


The PCI-e gen 4 limit is only kinda arbitrary, even Wendell mentioned in his testing, before the limit was added, that gen 4 was super unstable at best. The boards weren’t built to the spec required to run gen 4 stably and AMD decided it was safer to disable it rather than have customers trying to use something that unstable. So it is arbitrary but even without the software limit in place a b450 could never be recommended for someone that needs gen 4.


Is upgrading just the CPU a thing, even? Do people ebay their old ones then? Dad always keeps CPU/mobo/RAM together and upgrades them as a set, with the old set getting repurposed or sometimes given to another family member etc.

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So x470/b450 wont support pcie 4.0, but x570 and b550 do. This was an incentive for people to buy gen 4 if they needed/wanted it at a higher price bracket. I have not noticed a difference in performance though between my 3900x on my x570 crosshair vs my x470 crosshair. So yea it is what it is.

Well there have been some rumors that the Ryzen 4000 series cpu’s,
might be backwards compatible with 500 series boards.
However those are basically still rumors as far as i know.
So yeah i cannot really say anything for sure on that yet.

I mean AMD suddently came with XT cpu´s out of the blue.
Am4 to be officially eol in 2020 according to their original roadmap.
So yeah who knows…

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