I've been troubleshooting a downed miner, and narrowed it down to one Asus R9 280x card.  Numerous systems won't boot as soon as it is plugged in.  Have tried both sides of the bios. 
Will boot to DOS from a usb key.  On *nix, I can get to grub, and select an item - but then the system reboots without intervention.

atiflash -t (test rom access to card) results in PASS.

Any ideas what I can try next?