Comment by Aurornis
2 days ago
Adding the RAM to the system this way isn’t exactly like expanding the main system RAM. The RAM is connected over a PCIe type link so it doesn’t behave like the primary RAM.
It’s better for server farms where engineers can customize and tune for an architecture like this.
There have been some cards that use RAM as a storage device. They were never popular because having to set it up as a disk had very limited use cases.
To someone not familiar with CXL that still gives the wrong impression. As far as I have seen, CXL is supposed to be cache coherent, and should require less invasive rework (if any at all) of applications to take advantage of it; that's part of the enablement of memory disaggregation that CXL is pushing towards (similar to the storage disaggregation push a decade or so ago).
True, but it’s still another level of NUMA with lower throughput and higher latency. In consumer boards with limited extra high speed lanes it could be a lot slower than main DDR5 RAM. Wouldn’t be fun to have your game or app run a lot slower if it happened to be loaded into the wrong part of memory.