Bought to improve performance on my MacPro, worse than existing internal SATA bus
Uses standard benchmark tools, slower than the same drives connected to the internal bus, honest waste of money, not even worth returning, too much trouble to disassemble the computer again, just forget it.
Pros
Operating system software can be installed on an attached SSD, and booting the operating system from an installed PCIE drive is supported (Your motherboard BIOS must have this capability support)