Love this OS.   

I've been using a new mobo:  Biostar Z270GT6; got it to work all day yesterday on 5 GPUs.  Tinkered a bit today, tried to boot mobo, got pass BIOS screen, then got spammed with PCIE bus error severity=corrected.  It just spammed and spammed non stop, and would probably never stop if I hadn't powered down. 

A similar issue that is answered can be found here: https://askubuntu.com/questions/771899/pcie-bus-error-severity-corrected 

PS:  32GB USB still has some imaging issues, I've tried reformatting without the "quick" option, and tried both NTFS and FAT32.