The Quartus® II software may not merge independent multipliers into one or two DSP Blocks when using the Cyclone® V, Arria® V, and Stratix® V device families.
For example:
Three 9x9 independent multipliers are fit into three DSP Blocks instead of merged into one DSP Block.
Two 16x16 independent multipliers are fit into two DSP Blocks instead of merged into one DSP Block.
Three 18x18 independent multipliers are fit into three DSP Block instead of merged into two DSP Block.
The merging of independent multipliers will automatically take effect when Quartus® II software has determined insufficient DSP Blocks on the device or within a LogicLock region.