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If you're using an NVMe M.2 SSD, then no issues at all. The warning is, if you use a SATA M.2 SSD in the M.2_1 socket, then the M.2_1 socket shares bandwidth with SATA6G_1, SATA6G_2 ports, so you wouldn't be able to attach any SATA devices to those connections as they become disabled. But you CAN connect SATA devices to the other remaining SATA headers.