Worth noting that cards such as this (with mote than one M.2 slot) require the mainboard to support PCIe bifurcation – which most old boards likely do not.
Edit: Cards with just one slot do not require this feature so you can plug them into any board that has a free PCIe slot. Unless you also want to boot from them, in which case you might need to modify your UEFI. I went that route and succeeded, but be aware of the risks involved.
Worth noting that cards such as this (with mote than one M.2 slot) require the mainboard to support PCIe bifurcation – which most old boards likely do not.
Edit: Cards with just one slot do not require this feature so you can plug them into any board that has a free PCIe slot. Unless you also want to boot from them, in which case you might need to modify your UEFI. I went that route and succeeded, but be aware of the risks involved.