This thread had many suggestions that look like good leads for you to follow up with.
Things to try
idea #1 - systemd
If your system uses systemd try using this:
$ systemctl poweroff
idea #2 - blacklist kernel module mei_me
This mei_me ( Intel Management Engine Interface) for Mobile Intel Express Chipset, causes a lot of trouble.
You can blacklist the module, you could lose functionality that I'm not aware of.
If your laptop supports it you may be able to disable it in your BIOS.
I read people having success disabling it, though their all different issues.
idea #3 - interrogate journalctl boot messages
Take a look at the journalctl
for feedback on what's causing the system to reboot.
$ sudo journalctl -b
idea #4 - Add kernel parameter acpi=force
Try adding the following to your kernel's boot parameters. These can be appended to the end of your kernel's line in /etc/grub2.cfg
.
linux /vmlinuz-3.14.4-100.fc19.x86_64 root=/dev/mapper/fedora_greeneggs-root ro rd.md=0 ... acpi=force ...
idea #5 - Try a different power supply (larger rated)
My power supply was 450W. However, I got tired of going around the head until I read on page 23 of the GA-Z87N-WIFI manual which case we use the PCI-E was advisable to use a power supply of 500W or higher, as lower springs would destabilize (possible cause of the reboot).
Made to upgrade to a 650W power supply and reboots after shutdown, never happened.
Conclusion: new graphics cards are hungry for energy. Always check the power requirements of the printing and adjust energy sources.
idea #6 - disable WOL (Wake On LAN)
By default, the Wake-up LAN is enabled in BIOS (Power Manegement). As I have a Synology NAS configured for my private network, the "trickster" is sending packets to the network and enables me to Linux machine after doing this shutdown.
I followed your recommendation (I disabled the Wake-up LAN) and everything works as expected.
idea #7 - bug in kernel with xhci module
xhci: Fix spurious wakeups after S5 on Haswell
Source Bug 66171 - [PATCH]Poweroff doesn't work, it just reboots