Have you tried this:Ref: http://download.intel.com/support/ssdc/hpssd/sb/nvme_boot_guide_332098001us.pdf http://download.intel.com/support/ssdc/hpssd/sb/nvme_boot_guide_332098001us.pdfV.
Have you tried changing Secure Boot to "Other OS"? This issue is an interesting one because there are at least two people saying that a Sabertooth X79 and a P9X79, both with original unmodified bios 4801, dated from 2014/07/21,can boot the Intel 750:...
Very weird, but this kind of error is typical of a missing driver. I suggest downloading the last NVMe driver from Intel in a formatted USB flash drive: https://downloadcenter.intel.com/download/23929/Intel-Solid-State-Drive-Data-Center-Family-for-NV...
Hi Jonathan,Thanks for confirming that behaviour, and having a DC P3700 drive, that (LED is ON in idle mode), I can confirm this also applies to DC P3XXX series, at least.