The ECS Z77H2-AX comes with three PCI Express 3.0/2.0 x16 slots, two PCI Express 2.0 x1 slots, two standard PCI slots, and one mini PCI Express slot.
Usually, on motherboards based on the Z77 chipset, the first two PCI Express x16 slots are controlled by the CPU; the third PCI Express x16 slot is controlled by the chipset, operating at a lower speed (almost always x4). On this motherboard, however, thanks to the use of a PLX PEX8747 switch chip, the third PCI Express slot is connected to the CPU, is compatible with PCI Express 3.0, and can work at x8 speed.
Unfortunately, the product manual doesn’t mention the actual speeds of the PCI Express x16 slots. However, reading the product brief for the PLX PEX8747 switch chip, we can easily assume that the first two slots work at x16 speed when two video cards are installed (and not x8 as on most Z77-based motherboards), and the second and third slots work at x8 when three video cards are installed, while the first slot always works at x16. This is a phenomenal configuration. We simply don’t understand why ECS is not clearly explaining this important feature on its website and in its manual.
Since the slots are controlled by the CPU, they will offer PCI Express 2.0 bandwidth (8 GB/s at x16) when a “Sandy Bridge” CPU is installed, but PCI Express 3.0 bandwidth (16 GB/s at x16) when an “Ivy Bridge” CPU is used.
The PCI Express x16 slots support both SLI and CrossFireX technologies.
Since the Z77 chipset doesn’t support standard PCI slots, these slots are connected to PCI Express x1 lanes using an ITE IT8893 bridge chip.
Another highlight of this motherboard is the presence of a mini PCI Express slot. This slot allows you to install an SSD unit or a wireless network card based on this form factor.