I recently bought a Dell XPS 9550 and have been having issues with getting Intel SRT to work on it. I have been going at it with Dell Tech Support on this issue, and they honestly don't seem to know anything about it.
500GB Seagate primary disk
30GB LiteOn SSD cache drive
Windows 10 Home
RAID is enabled
The XPS came out of the box with W10 installed directly to the SSD. It took disabling the M.2 slot in BIOS to get the Dell Recovery software to correctly install to the 500GB disk. The Dell Recovery software included did not include any drivers. I immediately installed IRST and checked to see if I could enable SRT (nope). I tried formatting the SSD Cache all kinds of different ways (unallocated, RAW, NTFS, unmounted, mounted, forced id set as hibernation pagefile, etc). Nothing. Tried using both the newest Dell IRST drivers for my service tag, and the latest drivers direct from Intel. Also nothing.
Dell Support thinks this is normal operation in the IRST Control Panel (that SSD Caching is functioning correctly):
I'm pretty sure they are wrong, that I should have an option to actually enable/disable SRT and configure it as I want.