I have the GA-Z97X-UD3H-BK (rev. 1.0) with bios version F8 (latest) with the i7-4790K CPU and 16GB memory.

When I boot from my trusty 6Gbps SSD with Ubuntu installed in legacy BIOS mode (times are total elapsed time from when I press the On button):

  • 0sec American Megatrends
  • 4sec purple screen
  • 8sec Ubuntu login prompt

When I unplug the SATA cables from my drives and plug in the 512GB Samsung 950 Pro PCIe NVMe M.2 drive with the Lycom DT-120 M.2 PCIe 3.0 x4 Adapter:

  • 00min American Megatrends
  • 04min purple screen
  • 06min grub screen
  • 30min Ubuntu login prompt

Yes, the times in the first list are seconds and in the second list they are minutes. Once booted, the system is incredibly fast. The whole Ubuntu install from USB took about 4 minutes. When I test the drive speed I get:

  • 2.3GB/s (18Gb/s) read speed
  • 1.1GB/s (8.8Gb/s) write speed

That's about 90% of the advertised read speed and 80% of the write speed - pretty cool! How can a drive that's so fast be so S-L-O-W to boot? A friend said he only got his Samsung 950 to boot in UEFI mode which is why I went that route.

If I plug in the Ubuntu 16.04 USB installer, it boots from the Samsung 950 in seconds. Maybe the motherboard/bios doesn't like UEFI?

  • Check System > Administration > Log File Viewer > Messages. It may show something lagging or stalling before it backgrounds the process while booting. – Android Dev May 8 '16 at 14:16

The answer was to unplug my video card and just use built-in video on the motherboard. The Intel video card has a little bug where it dims the screen when I take a screen shot, but otherwise it's worked fine for me for a few months now.

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