890GX Features and Specifications
890GX Features and Specifications
As with any new platform, we’ll turn things over to the customary block diagram.
As with all of AMD’s platforms, the 800 series is a dual-chip solution encompassing the 890GX controller hub – we don’t feel right calling it a northbridge any more as the memory controller resides in the CPU – as well as the SB850 southbridge. As expected, the duties of 890GX include CPU interface, PCI-Express I/O control as well as graphics processing via the integrated graphics core dubbed Radeon HD 4290. You may notice that there isn’t much detail on the IGP depicted above, but not to worry, we’ll cover that in detail shortly.
You may notice that there is no mention of DDR2, only DDR3 and socket AM3 in the block diagram. Unlike earlier IGP platforms, it appears that AMD will be targeting the 890GX to AM3 based DDR3 systems – particularly with their new AM3 based Athlon II line of CPUs. Since memory control is exclusive to the CPU, and the CPU interfaces with the chipset using the same Hypertransport 3.0 bus, there is technically no reason that the 890GX couldn’t be adapted for use with AM2+ based systems. We’ll have to wait and see what board partners decide to produce, but we wouldn’t be surprised if the 890GX platform remains exclusively AM3, which makes sense as that seems to be the market direction – even for budget systems.
Let’s begin with the PCI-Express configuration supported by the 890GX. Like it’s predecessor, the 790GX, the 890GX has a healthy array of PCI Express 2.0 lanes, including a 16X 2.0 lane that can be evenly split into two 8X 2.0 lanes for Crossfire-X configurations. This was certainly nice to see, as the lower end 785G chipset couldn’t split it’s 16X lane, and users are forced to more of a crippling 16x4 configuration that could be limiting with higher end cards. A dual 8X configuration gives buyers a lot of flexibility. Not only can they begin with nothing but integrated graphics, but they can move all the way up to a pair of HD 5850s if they so desire.
Aside from the graphics card lanes, there are a total of six additional 1X 2.0 lanes available for integrated components – like audio and network controllers – and additional slots. If this weren’t enough, two more 1X 2.0 lanes are provided by the SB850 southbridge.
Moving on down to the shiny new SB850, we see that AMD has updated the chipset interconnect and is now using a 2GB/s interface dubbed “Alink Express III”. Although we’re not sure exactly what has changed, the older Alink Express II was essentially a 4X PCI-Express 1.1 lane, so bandwidth appears to have been increased – likely to a 4X 2.0 lane - for improved chipset to chipset communication performance.
Speaking of the southbridge, the most significant new feature that is has brought to the table is 6Gbps SATA support. That’s right, those lucky enough to own one of the new Sandforce 1500 based SSDs can now enjoy Read/Write well beyond 300MB/s. Aside from updated SATA support, the remainder of the southbridge is consistent with the older SB750. We unfortunately don’t get to enjoy integrated USB 3.0 support at this point in time, as the SB850 remains a USB 2.0 controller.
On the topic of USB 3.0, we should note that AMD was very careful to point out that USB 3.0 controllers can be interfaced to the chipset using 1X PCI-Express 2.0 lanes for a maximum theoretical throughput of 500MB/s. Coincidentally, Intel’s new H55 and H57 are limited to half bandwidth lanes and a maximum of 250MB/s to off-chip USB 3.0 and SATA 3.0 controllers. This likely won’t be of concern for USB 3.0, but having on-chip SATA 3.0 support is certainly a benefit as the only bottleneck is the 2GB/s Alink interface between the chipsets and 1X component interface lanes don’t need to be used at all.
So with that out of the way, let’s take a closer look at the new Radeon HD 4290 integrated GPU.
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