XPS 2720 - Replace 32Gb SSD with 500Gb SSD to use as boot drive

I bought a new 500Gb mSATA SSD with the intention of replacing the existing 32Gb SSD but instead of using it for caching as is currently the case, I would want it to be my boot drive. I got it from crucial and they supplied a license for acronis to assist with mgirating my data.

But when I tried to replace it, and I changed from RAID to AHCI in the BIOS, the system could not boot (inaccessible Boot device). Even with the 32Gb SSD, it will not boot if set to AHCI. It only works when set to RAID. I would have thought that my 1TB HDD was the Boot drive and so this should allow the system to boot while allowing me access the SSD within Windows where I could transfer a disk image and set the SSD as the boot device.

Is there any step-by-step guide available which will allow me to do this without the need to start again from a clean install. I am running Windows 10 and would rather not start again at Windows 8 and upgrade again.

All help would be greatly appreciated.