I don't know why but the video card is not enough.
Does your cards burn?

07: 00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD / ATI] Tahiti XT [Radeon HD 7970/8970 OEM / R9 280X]
08: 00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD / ATI] Tahiti XT [Radeon HD 7970/8970 OEM / R9 280X]

there is such a sign.

does claymore recognize cards as ellesmere