Anyone getting MCE errors and a reboot after a cold boot with a 2700X on Linux?

[loinad]

So, guys, I've had my new rig with a 2700X for a few weeks, and it seems totally stable both under Windows and Linux (be it under load or at idle), except for the fact that the first time I try booting Linux (either Fedora 28 with the 4.16+ kernel or Ubuntu 18.04 with the 4.14+ kernel) the machine reboots, and then the second boot succeeds, but I see many MCE warnings during the process. Any tips or similar experiences? :/