X38 chipset will be a bit bigger than the rest of its family that includes P35, Q31 and G33. These series 3 chips are 34x34 chips but the new X38 is a bit bigger.

This can be explained by a PCIe 2.0 support and presence of two PCIe 16X slots and some other better overclocking features but it could be that the packaging of the chipset is simply bigger to offer better cooling.

This definitely means that X38 boards requires a new design and it won't be just a refurbished P35 design. This is why X38 will be a significantly better overclocker.

The only thing that X38 needs is SLI support and even if it's technically possible Nvidia still didn't give Intel a green light.