The A75 chipset - Socket FM1

The A75 chipset

Despite the fact Llano already has an embedded Northbridge, the motherboards do need some sort of a Southbridge for external connectivity and other controllers. This takes the form of the A75 chipset, also known as the Southbridge or FCH. It connects from the APU's PCI-Express 2.0 bus over four links to the A75 chipset.

The feature set is pretty impressive as up-to six SATA-600 ports are supported with support for RAID 0, 1 and 10. That is alongside 10 USB 2.0 ports, 2 USB 1.1 ports and yes, USB 3.0 leads natively straight out of the A75 chipset as well with four USB 3.0 ports. Obviously the chipset also offers support for the older PCI slot, up-to three of them.

This is all embedded inside the FCH, thus motherboard manufacturers do not have to purchase extra USB 3.0 and SATA controllers, making the bill of materials a chunk smaller and cheaper.

Socket FM1

An interesting point with Llano processors is that AMD introduces a new socket - FM1. This was to be expected given that the silicon features both a CPU and GPU. Maintaining AM3+ compatibility couldnt really be expected.

FM1 processors have 905 pins by the way.

Whereas Bulldozer processors will use Socket AM3+, A4, A6 and A8 Llano processors will make use of FM1. Now, it's good to know that all current AMD coolers will fit perfectly onto this new slot. So there is no need to invest in new CPU (APU) coolers.

Above, a block diagram of the A75 chipset features. Quite an extensive list for entry level to mainstream PC products alright.