https://www.techpowerup.com/290386/asus-is-working-on-a-ddr4-ram-adapter-for-ddr5-motherboards
 
With the current short supply and maybe more importantly, the rather insane pricing for DDR5 memory, ASUS is working on what could be called a quick fix for the problem, an adapter that would allow DDR5 motherboard owners to put DDR4 memory in their motherboards. It's not what we'd call an elegant solution at this point, but it's said it'll be refined before it's ready for retail—if it ever enters the market—since apparently the engineer that developed the adapter doesn't always get to see his projects hit retail, as from our understanding he's responsible for a lot of the more unusual products from ASUS' ROG brand.

That said, considering that a lot of high-end Z690 motherboards only support DDR5, this might be an interim solution that makes sense for a lot of people until availability of DDR5 improves. There's some complexity in making the adapter work though, as not only does it need its own power regulation, since DDR4 memory doesn't have onboard power conversion components unlike DDR5, but there's also the 2x 32-bit vs 64-bit bus to take into consideration as well. On top of this, the DRAM traces are obviously extended, which could lead to instabilities, which is why it's apparently only tested with one type of memory right now, which appears to be G-Skill's Tridentz Royal. A further limitation of the adapter is that it requires a special UEFI version to be installed that allows DDR4 memory to be used, but this might be the smallest issue in this "skunk works" project from ASUS' ROG team.
 
Personally I think the complexity of this device probably means it won't make it to market anytime soon. 
 

That's a smart idea.
I like seeing a prototype with a bodge wire.
It looks like most of the height is there to allow a SATA power connector to be plugged into its side. If they decide that it doesn't need the extra power, the height should be able to easily be reduced.

That would block a lot of airflow but probably a lot of buyers already would have DDR4 so it could be a great solution to save them money until DDR5 prices drop.
 
I am wondering if it would work on other motherboards or if the bios would have to recognize it and Asus would use that to keep it to themselves. 

Adapters are a bad thing. Don't see this going well.

Surely there will be some loss of performance as you're running ddr4 on a ddr5 board. I could see instability being an issue too.

Sajin
Surely there will be some loss of performance as you're running ddr4 on a ddr5 board. I could see instability being an issue too.

I would assume that it is for people who don't have another choice. Performance reduction is 100% certain.
You already have a motherboard? You already have a CPU? You are just waiting for DDR5 memory to be available? There's this adapter to get you going in the meantime...

Hoggle
 but without memory you don't have a working computer.
 

Yup, and a working computer is better than no computer.

They have to do something. I won’t buy a board until I can buy RAM at MSRP which is already outrageous.