Apple Xserve (Early 2009): Has anyone installed PCIe SSD in PCI-E slot?
I'm running a 2009 Xserve on a Plextor M6e 256GB (PX-AG256M6e) and it works great. I also just installed 10.11.6 on a Samsung SM951, AHCI version (PN MZHPV256HDGL). As far as I can tell, it must be the AHCI version and not the NVMe version to work. I put it on a StarTech PEX4M2E1 M.2 PCIe adapter. Both of these put the original SSD to shame in terms of performance.