Are they detected by any kind of related software? Could it be that this is a driver related issue by any chance? Make sure you've checked those before "baking" them.
Fully checked. They should have at least post when booting before going to the OS. They don't post at all. Even without drives they should have been detected using `lspci ` but they do not show up in either Ubuntu 15.04 or 16.04. They don't even post to allow you to enter the BIOS.
The same system runs 1X 390 2x 295 that I used to check these cards.