Intel is getting ready to bring its Optane memory to market, which will help speed up storage drives in Kaby Lake systems, even those slow spinning 5,400 RPM hard drives. However, it appears you'll need a Core i3-7100 or higher CPU in order to use it.
Optane memory uses Intel's 3D XPoint technology and acts as sort of a high-speed SSD cache for your storage. Initially it will be offered in 16GB and 32GB modules. These will plug into compatible motherboards. As with other caching solutions (such as those that exist on hybrid hard drives) it will learn your usage patterns and ultimately make your system more responsive by moving frequently accessed data into the faster cache.
Since reporting on this earlier this week, it's come to light that Kaby Lake Pentium and Celeron chips may not support Optane memory. The folks at TechReport dug their noses into Intel's ARK database and noticed that every processor below a Core i3-7100 did not list compatibility. That includes the Celeron G3930, Celeron G3950, Pentium G4560, Pentium G4600, and Pentium G4620. Same goes for lower power "T" versions of those CPUs.
If true, this is likely Intel's way of limiting Optane memory to higher-end parts under the assumption that budget builders may not be keen on paying $45 or $77 for a 16GB or 32GB module, respectively.
The good news for budget builders who are interested in Optane memory is that the Core i3-7100 is not super expensive. It retails for $120, so it would still be possible to piece together a relatively affordable system and still use Optane memory.