SB850 is AMD's latest, greatest Southbridge and this chip looks like a big improvement compared to SB750.
The new Southbridge brings A-link with X4 Gen 2, PCIe 4x1
Gen 2 as well as 14+2 USB 2.0 ports. The previous SB750 only had 12+2, which
should be enough, but hey more is usually better. SATA gets upgraded to 6x 6Gb/s
which is another name for SATA 3.0 and of course RAID 0,1,5 and 10 support is
here. It also has integrated clock generation and Gigabit MAC.
The new Southbridge comes in new FCBGA 605 pin package and its TDP is 4.0 W. AMD SB750 has TDP of 4.5 watts and less features. SB850 should launch in Q4 together with RD890.