Setting up RST cache with an ssd?

My current setup has a 250gb samsung 840 evo ssd which has my os on it and 3tb seagate hdd for main storage....i recently purchased an additional 120gb samsung 840 evo ssd to use as a cache for the hdd but i cant figure out how to setup only the new ssd as a cache for the hdd

i attempted to change the sata controller from ahci to raid but kept gettting bsod.

any help with this would be greatly appreciated

Read your motherboard's manual.