T-Break posted a review on the ASUS P5W DH & M2N32-SLI Motherboard

Both these boards have two PCI-E x16 slots, however, the M2N32 provides dedicated x16 lanes to both these slots and only works with an SLI multi-GPU setup. On the other hand, the P5W DH, provides x8 lanes if both the PCI-E x16 slots are used and only supports CrossFire technology for a multi-GPU solution.

ASUS P5W DH & M2N32-SLI Motherboard Review