Next I bought this https://eshop.macsales.com/item/OWC/SSDACL6G.S/
Since my investment was substancial at this point with no joy I didn't purchase the recommended Samsung SSD but used a Kingston 90GB SSDnow 200 I had laying around to test.
I installed it in slot 7, I will move it to the top slot as you suggested. Yes, RAID + AHCI is set in the BIOS. Nothing new appeared to set the boot order. I will make sure I'm using the Intel driver you suggested and report back.
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Yes, this setup should work. Make the SSD your primary boot device in bios settings.