I am using eMMC SKU and noticed there is no Ready Boost tab shows up even I connect USB memory.
So, I checked some devices and concluded as below.

eMMC storage device => Ready Boost cannot be enabled since Ready Boost tab wont show up.
SSD storage device => Ready Boost cannot be enabled since Ready Boost shows like Not supported Ready Boost since already PC is very fast
HDD storage device => Ready Boost can be enabled.

But not sure this my understanding is really corect or not.
Please kindly help if my understanding is OK or not.

eMMC is different than SSD http://www.howtogeek.com/196541/emmc-vs.-ssd-not-all-solid-state-storage-is-equal/

Readyboosts benifits are here https://technet.microsoft.com/en-us/magazine/ff356869.aspx

Is readyboost worth using is here http://www.howtogeek.com/123780/htg-explains-is-readyboost-worth-using/

Hi,

When you first insert any Flash Memory device, Windows will automatically check the device for Ready Boost compatibility. If the device does not meet the minimum requirements, then it will be disabled for that device.

Here are the minimum requirements.

The USB Key must be at least USB 2.0

The device must be able to do 3.5 MB/s for 4 KB random reads uniformly across the entire device and 2.5 MB/s for 512 KB random writes uniformly across the device.

The USB Key has to have at least 64mb of free space

In addition, the SuperFetch Service must be enabled and set to start automatically.

Ready Boost will not provide a performance when the primary disk is an SSD, Windows 7 disables Ready Boost when reading from an SSD drive. I dont think Windows 8.1 will change that. And for eMMC (classed as SSD), this option also won't appear as I know.

Understand Ready Boost and whether it will Speed Up your System

https://technet.microsoft.com/en-us/magazine/ff356869.aspx

Regards,