PCI Express

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Revolutionary PCI Express interface provides scalable bandwidth for multi-purpose usage. [COLOR=#ff0000][/COLOR][COLOR=#ff0000]PCI-E x16 interface (The GA-M61VME-S2 supports up to PCI Express x1 mode, please refer to the VGA cards support list)[/COLOR] doubles the bandwidth of graphics interface of previous generation thus delivering the utmost gaming experience. PCI-E x1interface provides twice the bandwidth of PCI interface up to 250MB/s for new generation I/O peripheral devices.

My motherboard has a PCI-E x 16 interface but supports up to PCI Express x1 mode.
What is the meaning of this?