Hello Jonathan,
Saturday, May 12, 2018, 9:39:01 PM, you wrote:
At a bare minimum, I'd try using CentOS 7 1804: http://isoredirect.centos.org/centos/7/isos/x86_64/
thanks; after some waiting time, 1804 now keeps repeating "dracut initqueue timeout - starting timeout scripts" for a while, then drops into the emergency shell. no suspicious error messages in the log.
did change SATA mode from ATA to AHCI in the BIOS, but this didn't change anything.