The Radeon Xpress 200 chipsets supports 22 PCI Express lanes with 16 of these dedicated to the x16 PCI Express graphics slot, while four can be used to either provide expansion slots or onboard peripherals. Interestingly the ATI SB400 south bridge is connected to the north bridge via two PCI Express lanes, something that is usually done over a proprietary bus. Two PCI Express lanes should however provide more than enough bandwidth for the integrated devices in the SB400 south bridge, as it doesnâ€™t feature integrated LAN.
What the SB400 south bridge does have on offer is native support for up to four SATA 150 devices and four IDE devices, up to eight USB 2.0 ports and 8-channel AC97 audio. The SATA controller supports RAID 0 and 1, but not 0+1. Hopefully ATI will bring out a south bridge with integrated high-end audio and Ethernet at a later stage, since these are features that one would expect from any current motherboard chipset.
The reference board that ATI supplied for testing featured a lot of extra connectors and sockets which are used for chipset validation and final production boards will look much cleaner. Several motherboard manufacturers are already preparing to launch products based on both versions of the chipset and some might even be available before Christmas.
So what about the performance? Well, we tested the board using an Athlon 64 4000+ processor and the results are pretty encouraging, especially if production boards improve upon the scores that the reference board produced. What impressed me the most was the small difference in SYSMark 2004 between the integrated graphics and a discreet graphics card. A score of 194 was obtained using the integrated graphics; while a mere one point was gained using a Radeon X700 Pro card.
This is however not true for the remaining benchmarks, as in PCMark 2004 the scores were a fair bit lower using the integrated graphics. Oddly enough the memory test would crash out in PCMark 2004, although all the other tests completed just fine, whether the integrated graphics were used or not. The 3D scores are far from great, but at least a playable frame rate of 34.2 fps was obtained in Unreal Tournament 2004.
With the supplied Radeon X700 Pro card the scores were however much better and the Radeon Xpress 200 chipset is as viable an option as a VIA or nVidia chipset for a PCI Express based Athlon 64 system. The only downside is the low feature count, especially the lack of an integrated network adapter, but hopefully ATI will address this in the very near future.
Overall the Radeon Xpress 200 impressed us and I would expect to see it in a fair few laptops, as we did with the Radeon 9100 Pro IGP on the Pentium 4 side. Hopefully it will also help speed up the transition to PCI Express enabled laptops for AMD. One aspect that remains to be seen is the price of retail boards, as this will of course influence the final buying decision.
The Radeon Xpress 200 shows that ATI is dedicated to its chipset business, even though it will take some more effort to truly compete with the more established chipset manufacturers. It is however great to see that ATI has brought the first integrated chipset with PCI Express for Athlon 64 to market before anyone else.