It's definitiely not an issue of "trying to boot" with no bootable device. It doesn't even TRY to boot with the RR + > 0 drives. Just shows the "Dell Ball".
No boot failed message, no HDD Failure message, no missing OS, no ntoskrnl not found, no blinking cursor in the top LHS corner. No blinkenlietz BIOS diagnostics. Just a big ol' Dell in the middle of the screen.
The RR people say there's a resource conflict. After I try their fix I'll follow up.