XPS 8700 ORIGINAL CONFIGURATION

It would originally have shipped with Windows 8 or 8.1 (installed on the hard drive, as the mSATA drive is just a cache).

Thanks. What software configuration is required when doing a clean OS install, in order for the cache ssd to work? 

If it came with Windows-8.0/8.1, best config would be Windows-10 64bit ... installed to a bootable SSD (as the C-Drive). Might actually run pretty good and the high speed and IOPS for a real-SSD would help offset the slower-speed of the main processor.

The performance of a 2.5in SATA-3/600 SSD is about the same as any other implementation of SATA (mSATA, M.2-Sata, or whatever).

I have upgraded my XPS8700 in the following ways: 1.windows 11pro (by way of rufus)

                                                                                 : 2. 32GB of RAM           

                                                                                : 3 1TB of SSD Hard Drive

                                                                               :  4. Dual Blue Ray Disc Record/Play

in other words it can be done! it cane with an AMD GPU i was trying to replace it, but i cant find an upgrade. 

@krrrrazyk​  If you don't use Rufus to install Win11 Pro, it might still be possible to load Win10 on a flash drive from a working PC using the Microsoft site.  Then load Win10 on SSD from flash drive.

If OP has upgraded to 1TB ssd there is no need to use the old Intel rapid storage to set up ssd as cache for hdd. That was old times when a small ssd teams up with large hdd. In those old days large ssd was still too expensive to deploy thus the industry created a RST scheme.

Thank you everyone for weighing in. I installed a new ssd, and so far, its working fine, with the exception of a long boot time, 50% of the time.