The Samsung B-die memory chips are a favorite among overclockers but it looks like this story is coming to an end as the latest version of Samsung's Product Guide reveals the firm killed this line. As reported by Tom's Hardware, Samsung will now offer a new A-die chip series with higher chip density:
The new A-Die offers the advantage of higher available chip density, particularly to module assemblers/programmers (i.e., the companies we’re accustomed to supplying our XMP-rated DIMMs). The 16Gb (sixteen gigabit) M-Die chips that were supposed to have brought us 32GB consumer DIMMs a year ago appear to have been reserved for Samsung’s own-brand modules, and the best guess from our suppliers has been that the server sector has drawn that supply dry.
At the moment, it's unknown whether the new A-die chips will offer the same overclockability as the B-die products.