As Tweeted by @9550pro, a new ROG DDR5 to DDR4 adapter appears to be in development by Asus. Chinese YouTuber 林大餅Bing made a video discussing this new DDR5 conversion card and how it works.
ROG DDR4 to DDR5 adapter😬https://t.co/fcHRkOZwmr pic.twitter.com/xFhoSKGwjEDecember 30, 2021
According to the video, this is an experimental DDR5 to DDR4 card. The YouTuber explains that the card can successfully convert a DDR5 slot to communicate DDR4 signaling to both the CPU and memory module. However, due to the card's immense size, the traces connecting the DDR4 module to the DIMM slot are very long, which can make running high-speed memory modules problematic.
One reason for the card's tall form factor is due to the power delivery system required to operate the DDR4 modules. Because of the power delivery changes to DDR5, motherboards are no longer responsible for filtering and delivering clean power to the DDR5 memory modules. This means the conversion card also needs to serve as a power delivery system for the DDR4 modules that lack built-in VRM.
The only reason such a card can work in the first place is thanks to Intel's Alder Lake platform supporting both DDR4 and DDR5 natively. When using the conversion card, the CPU will detect the DDR4 modules as DDR4 memory, meaning the card isn't tricking the motherboard into thinking the DDR4 modules are DDR5.
In the video, the YouTuber demonstrated a test boot, proving that the converter card is functional and that the modules are correctly identified as DDR4 in the BIOS.
We aren't sure when or if these converter cards will ever appear on the market. But, many people could benefit from such a card, given how expensive and rare DDR5 memory is right now.