As mentioned, the AMD 890FX chipset has 42 PCI Express x1 lanes controlled by 11 engines – just to put things into perspective, the AMD 890GX chipset has 22 lanes controlled by eight engines. This allows this chip to provide a very high-end slot configuration.

The Gigabyte 890FXA-UD7 comes with six PCI Express x16 slots (remember we wrote that the five slots on the MSI 890FXA-GD70 were an impressive number). The first one (PCIEX16_1) works at x16 if the third slot is empty; if it is used, both of them will work at x8. The fifth one (PCIEX16_2) works at x16 if the sixth one (PCIEX8_2) is empty; it will work at x8 if it is occupied. The second PCI Express x16 slot (PCIEX4_1) works at x4 all the time and the fourth one (PCIEX4_2) works at x1, unless you disable the extra SATA controller, when it will work at x4 speed.

The way that the PCI Express x16 slots are arranged was well-thought out. There is enough room between the slots for you to install dual-slot video cards in the first, third and fifth PCI Express x16 slots at the same time. A fourth dual-slot video card can be installed on the last PCI Express x16 slot, but only if you have a case with nive or more expansion slots (of course, in this case, it will block all the USB, serial, parallel and FireWire headers available). So, with the right case, you can have up to four dual-slot video cards installed at the same time with this motherboard, a configuration that is not possible to achieve with cheaper products.

It is important to note that motherboards from other manufacturers may use a different configuration.

This motherboard offers support for CrossFireX technology, but not for SLI. The product comes with two CrossFireX bridges.

The Gigabyte 890FXA-UD7 also comes with one standard PCI slot. The use of a dual-slot video card in the fifth PCI Express x16 slot will “kill” the standard PCI slot.

click to enlarge
Figure 2: Slots.