P55-GD80 Slot Configuration
With support for CrossFire and SLI, the first two PCI Express x16 slots on MSI's P55-GD80 are tied to the LGA 1156 interface. With one graphics card installed, the top slot gets all 16 of the CPU's available lanes. With two installed, the slots automatically revert to x8/x8. The third x16 slot runs to the P55 PCH and is wired to operate at x4 signaling rates. Bear in mind that if you populate the third slot, neither of the x1 slots will be usable. Why not? Doesn't P55 include eight lanes of PCI Express 2.0? Yes, it does. But MSI's integrated extras (networking/storage) utilize what's left. So, just keep the slot limitations in mind as you plan your upgrade path.
Two standard PCI slots round out expansion on the P55-GD80.