The Gigabyte Z77X-UP4 TH comes with three PCI Express 3.0/2.0 x16 slots, three PCI Express 2.0 x1 slots, one standard PCI slot, and one mSATA slot.

Usually, on motherboards based on the Z77 chipset, only the first two PCI Express x16 slots are controlled by the CPU. The other PCI Express x16 slots are controlled by the chipset, operating at a lower speed (almost always x4) and only compatible with the 2.0 specification, which offers half of the 3.0 bandwidth. On this motherboard, however, the three slots are controlled by the processor.

However, since socket LGA1155 Intel CPUs only offer 16 PCI Express 3.0 lanes, the speed configuration for these slots are as follows. If only the first PCI Express x16 slot (“PCIEX16”) is used, it operates at x16. If the first and the second PCI Express x16 slots (“PCIEX16” and “PCIEX8”) are used, both operate at x8 speed. And if the three PCI Express x16 slots are used, the first operates at x8 speed, but the other two operate at x4 speed. Also, the third PCI Express x16 slot only works when an “Ivy Bridge” CPU is installed; it is incompatible with “Sandy Bridge” processors.

When installing dual-slot video cards, you “kill” the slot immediately to the left (looking at the motherboard with its rear connectors facing up) of the slot being used. If a third dual-slot video card is installed (in the third PCI Express x16 slot), you will need a case with at least eight expansion slots.

The PCI Express x16 slots support both SLI and CrossFireX technologies.

Since the Intel Z77 chipset doesn’t support standard PCI slots, the Gigabyte Z77X-UP4 TH uses an ITE IT8892E bridge chip to connect the standard PCI slot to a PCI Express 2.0 x1 lane.

Gigabyte Z77X-UP4 TH motherboard Figure 2: Slots

The mSATA slot is not a Mini PCI Express slot, meaning you can’t install a Wi-Fi card in it. It is designed specifically for SSDs using the mSATA form factor. This slot is connected to the “SATA2 5” port, so you can’t use this SATA port when an mSATA SSD is installed. This slot uses a SATA-300 connection.

Gigabyte Z77X-UP4 TH motherboard Figure 3: The mSATA slot

In order to properly accommodate the Thunderbolt controller, the board makes use of a PLX PEX8605 switch chip. This chip automatically switches the available PCI Express lanes to the devices that need them. On motherboards with too many PCI Express devices without a switch chip, you need to manually disable devices on the motherboard setup in order to achieve full performance on devices connected to the USB 3.0, SATA-600, and Thunderbolt ports when transferring files at the same time.

Gigabyte Z77X-UP4 TH motherboard Figure 4: The PLX PEX8605 chip


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.