One of the main new features from socket 1156 processors is the presence of an integrated PCI Express 2.0 controller inside the CPU. This controller supports one x16 connection or two x8 connections. MSI P55A-GD65 has two PCI Express x16 slots using this configuration. They support CrossFireX, but not SLI. Keep in mind that SLI support on P55-based motherboards will depend on whether the manufacturer licensed this technology from NVIDIA or not.

The other PCI Express slots are controlled by the chipset, which has a total of eight PCI Express x1 lanes. A small but very important detail is that MSI added a PLX PEX8608 PCI Express switch chip on this motherboard (see this chip near the black PCI Express x1 slot in Figure 2), which adds eight more PCI Express x1 lanes to it. The presence of this chip allows you to run two high-end video cards, SATA-600 hard disk drives and USB 3.0 devices at the same time without any drop in performance. On motherboards without a chip like this, performance may drop under this type of load, as the chipset doesn’t have enough PCI Express lanes to connect all these devices at the same time at their full speed.

This motherboard has two PCI Express x1 slots and two standard PCI slots. The older P55-GD65 model has one PCI Express x4 slot, but the main difference between these two motherboards is the placement of the available slots. As you can see in Figure 2, MSI put the standard PCI slots between the two x16 PCI Express slots. On the original P55-GD65 you automatically “kill” one of the PCI Express x1 slots whenever you install a dual-slot video card in the first PCI Express x16 slot, a thing that doesn’t happen with this motherboard.

The slot configuration used on the P55A-GD65 is identical to the configuration used on the P55-GD85. The only difference between the two here is that the GD85 supports SLI, while the GD65 doesn’t.

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Figure 2: Slots