I can think of a better solution -- IF you cannot boot an NVME drive from the X79 motherboard. I realized this myself with a newer motherboard running an NVME M.2 boot-system drive.
You can socket up to 64GB of RAM in an ASUS Sabertooth (or similar) X79 motherboard.
If you have 16GB of RAM already, consider doubling it to 32 (or more!!!), but 16 will give you an idea of what you want or need. Buy a lifetime license to Romex Primo-Cache for ~ $30.
Then, cache your SATA SSD to some amount of RAM between 4 and 16GB. A benchmark like Anvil would then show you sustained sequential reads higher than 10,000 MB/s -- after initial execution of this or that program or OS component has occurred. And you can preserve the cache between "Restart" operations of the system.
If you can still add an NVME M.2 drive while booting from the SATA SSD, you could do that as well. But if it's a matter of dollars versus performance, the decision is purely subjective.
Unfortunately, RAM prices are high right now, but adding to RAM by buying an identical kit to what you have now should be competitive to the price of a small NVME M.2 -- between 256 and 512GB.
It's not for everyone, and we can't ignore that the X79 chipset is a bit dated. If it were I, hoping to extend the usefulness of my X79 board, I'd probably do it . . . .