Played around some today... and it seems the cable (old one) is suspect. Once on boot I saw the yellow triangle for a few seconds. Had a few clean starts and one bad one, cable disconnected.
Put in the new cable and it never had a problem.
Sooo, somehow the cable went bad? Maybe some build-up on the connector, wear, who knows, but I'll go with the new cable. See if that is OK. If it should start failing on boot, I'll have to look elsewhere I guess for a solution? NIC is on the motherboard and I guess I could try a PICe card if it should fail.