RE: HDD replaced with SSD on Xps 15 L521x with 32 gb ssd module, how to configure RST in bios
Alternatively, if you are not using the msata drive, then you could change the sata operation in BIOS from Intel Rapid Storage to AHCI. The IRST screen on startup will not come up then. However, changing the boot operation, might cause the system not to boot into Windows. You would then need to reinstall the OS.
Using the msata with the SDD is not recommended as advised by ejn63.
Also, please click my DELL-username and write me a private conversation with the service tag and your contact details(Name and Email) for case records.
Let us know if you have any other queries.