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#21
I checked. The Asus NX500 has an Intel HM87 chipset, which does not support NVME. (It was released in 2013.) There will be no BIOS updates to change that.
It may be hard to find a new PCI-E M.2 drive that is not NVME.
I see some stuff on the Web about hacking BIOSes for Intel chipsets that have no official support for NVME. That's way above my competence level, and it's not clear that anyone has done it for HM87.
You have my sympathy. It's too bad when hardware that is less than 5 years old becomes unsupported.