I talked to you before abut how hot these U.2 drives are, maybe use that Velociraptor 2,5 to 3,5 adaptor/heatsink?Ok so a big lesson learned. Im not sure if it's the drive or the PCI card, but the combo does not like to be put to sleep. If the drive goes to sleep, when you go to wake the system it hangs pretty hard.
The solution is to change the setting enable the "prevent the computer from going to sleep when the display is off" setting....and then it seems to wake and operate just fine. You do not seem to need to deselect the "Put hard disks to sleep when possible". So if I had to guess, the Highpoint 7120 PCI card is getting turned off and cannot recover gracefully?
I forgot that I had both the "dont sleep" and the "dont spin down" settings on on my cMP (dont even remember the reason why--I think my time machine drive wouldnt spin back up well if I let it sleep) but those settings seem to mess up a lot of hardware. But beware if this is an issue for you wrt to power consumption etc.
The drive seems to run warm. It runs around 131F. Not catastrophe but certainly toastier than I'd like. I found this online:
Supermicro Servers Support PCI-E SSD Solutions Intel® NVMe HGST SSDs Micron NVMewww.supermicro.com
So it's running within spec.