There are two core components in the 890GX chipset. First up is the Northbridge which contains the ATI 4290 GPU, a refresh of the 4200 which was present on the 785G. The 4290, like the 4200, contains 40 unified shaders and is a DirectX 10.1 part using the RV620 core. It can use a 64 or 128-bit memory interface and will generally come attached to DDR3 sideport memory ("performance cache"), though system RAM can also be shared with the GPU. ATI allow connection of up to 4 displays on the 4290 and these are DVI, HDMI, DisplayPort and VGA. As with all recent Radeons it is possible to output audio via the HDMI, in this case 5.1 channel and the chip fully supports Blu-Ray acceleration/AVIVO and UVD 2.0.
Partners have the option to connect two graphics slots to the 890GX, if one card is installed it runs at 16x. Two cards run in 8x mode. Six additional PCIE 1x lanes are available and there is a 5.2GT/s HyperTransport 3.0 link connecting the chipset to the AM3 socket.
Motherboard manufacturers will us the new 850 Southbridge with the 890GX Northbridge and link them via an Alink Express 3 bus running at 2GB/s. The SB850 offers consumers up to 14 USB 2.0 ports, PCI and PATA connectivity, GB LAN, 2xPCIe and HD audio but the biggest feature is native SATA 6GB/s support.
AMD claim that due to the design of the 890GX/SB850 platform that their implementation of SATA 6GB/s (and USB 3.0 when the controller uses a PCIe lane) offers significant bandwidth improvements over solutions from their competitors.