I've an update in this regard  As I couldn't sleep for a looooong time I made some further tests with my hardware. 1. power supply is not an issue as I could even power 3 regular 3,5" HDDs using y-cables 2. the M.2 interface on the motherboard also rejects to recognise a brand new M.2 22110 Optane SSD whereas others do work. The 22110 does work in my older 5040 Optiplex though so it's not DOA. Having a closer look at the M.2 connector it looks like the pins of the M.2 -> U.2 adapter do not have contact as compared to my 5040 it stands out for roughly have a millimeter. Some goes for the 22110. Did some research and found a M.2 extension cable from ADT-Link: [URL] Got it today and guess what? Both my U.2 SSD as well as the 22110 SSD do work while using this extension cable 
Hi, got a used Optiplex 5060 SFF today and wanted to boot up my Intel Optane 900p U.2 SSD (SSDPE21D280GASM - comes with a SFF-8639 to M.2 cable and adapter [the one at the bottom of this picture]) which works flawlessly in my current 5040 SFF.Unfortunately it didn't boot Windows 10 so I checked BIOS settings and figured out it didn't even get listed in the Slot3_M.2 entry. As the BIOS was quite old (1.2.17) I've upgraded to the most recent version 1.9.1 but also didn't help. Things I've checked so far: The 5060 SFF itself has the following components installed: Couldn't find anything related to such behaviour so far that's why I'm asking for some ideas  Device is already out of warranty so I cannot report anything official. Thanks in advance.  
Optiplex 5060 SFF BIOS does not recognise Intel U.2/SFF-8639 -> M.2 SSD