I have a Gigabyte X-79-UD5 with a 3930K that's been a solid workhorse for the past few years. Lately I've started having some odd glitches with startups and shutdowns that had me suspecting the boot loader (Clover, currently using 4049). I tried earlier versions with the same result.
The biggest issue is that when I call shutdown the machine restarts. I realize there are shutdown fixes, I've never needed one with this rig. I am booting in verbose mode, at shutdown I am seeing this message as part of the shutdown procedure;
com.apple.xpc.launchd[1] (com.apple.xpc.launchd.domain.system) <Notice>: Will be calling reboot(2) with flags: 0x0
Then the usual unmounts, cpu halted, a few seconds of silence then the machine restarts. Curiously this happens with a High Sierra and a separate El Capitan install on the same machine (separate Clover installs in the EFI on each of those separate drives.)
What's more curious and has me starting to wonder what the common factor is, is that I've started getting occasional Panics at boot. Doing a CMOS reset fixes this 100% of the time. Windows runs fine while this is happening (Windows 10 and 7, again on separate drives, though still loading with Clover) At one point I opened up the Bios screen at boot and saw Cyrillic (Russian) text in one of the fields, the reset fixed that.
Nothing has changed with the hardware config (except for perhaps age) or the EFI folder (except for some clover updates.) I thought perhaps something with the boot loader and some changes to how NVRam is handled may have been causing the problem, but rolling back didn't resolve it (NVRam has been no problem on this machine since it was supported by Clover a few years back)
Any suggestions?