MSI MS-7521 (v2.X) Manual page 27

Hardware Setup
Serial ATA Connector: SATA1~6
This connector is a high-speed Serial ATA interface port. Each connector can connect
to one Serial ATA device.
SATA2
SATA3 SATA1
SATA6 SATA5 SATA4
Important
Please do not fold the Serial ATA cable into 90-degree angle. Otherwise,
data loss may occur during transmission.
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