MSI X299 TOMAHAWK AC Quick Start Manual page 34

M.2 slots with examples of various combination possibilities
1xU.2+ 1xM.2 PCIe+ 1xM.2 SATA+
7xSATA
M.2 PCIe
M.2 SATA
1xM.2 PCIe+ 1xM.2 SATA+ 7xSATA
M.2 PCIe
M.2 SATA
1xU.2+ 2xM.2 PCIe+ 4xSATA
M.2 PCIe
M.2 PCIe
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Overview of Components
SATA7
SATA8
SATA7
SATA8
1xU.2+ 2xM.2 SATA+ 6xSATA
M.2 SATA
M.2 SATA
2xM.2 SATA+ 6xSATA
M.2 SATA
M.2 SATA
1xU.2+ 1xM.2 SATA+ 1xM.2 PCIe+
3xSATA
M.2 SATA
M.2 PCIe
SATA7
SATA8
SATA7
SATA8