As per subject I've just installed a Samsung 970 Evo and made it my bootable disk.

Start-up time is not much different from an SSD, shutdown time is taking 10+ minutes.

I am running Ubuntu 18.04.3 with HWE (kernel 5+) and I have *not* done a fresh install, but cloned from my previous SSD.

When the computer is up, performance is great (can reach 2+ GiB write per second), but boot is slow and, crucially, shutdown takes 10+ minutes.

Any idea why?
Am I the only one experiencing this?

My motherboard is an Aorus z370 with latest firmware.

**Edit**

As requested, these are the last log lines before the shutdown (from `/var/log/kern.log`):

```
...
Aug 26 14:23:08 scv kernel: [   25.907858] Bluetooth: RFCOMM socket layer initialized
Aug 26 14:23:08 scv kernel: [   25.907867] Bluetooth: RFCOMM ver 1.11
Aug 26 14:23:15 scv kernel: [   33.071042] rfkill: input handler disabled
Aug 26 14:24:41 scv kernel: [  118.685677] rfkill: input handler enabled

```

The computer shutdown around 14:28 - I'll try executing the kernel with `debug` option to see if I get a more insightful log.

**Edit 2**

After setting the kernel in debug mode, I can shutdown and what happens is that the keyboard switches off (it's a LED Razer), but not the main PC.

Funny enough, when I restart the count of `Unsafe Shutdowns:` with `sudo smartctl -x /dev/nvme0n1` is the same as before, which implies that it's just the motherboard which doesn't power down.

I'm going to test by using the SSD again and see what happens.

**Edit 3**

After trying to use my SSD instead of the NVMe, I realized even the SSD was taking ages to shutdown.
I have reverted the bios, and after some bisecting, I've found out the best version is [F13](http://download.gigabyte.eu/FileList/BIOS/mb_bios_z370-aorus-ultra-gaming_f13.zip), because [F14](http://download.gigabyte.eu/FileList/BIOS/mb_bios_z370-aorus-ultra-gaming_f14_n.zip) has the issue, but previous versions such as [F11](http://download.gigabyte.eu/FileList/BIOS/mb_bios_z370-aorus-ultra-gaming_f11.zip) are more unstable.

On a side note, my SSD broke after 30 minutes, I am sort of relieved I just moved the data to the NVMe.
Not sure if I should consider this lucky or not... :-)