Fortunately, however, Geoff's extensive south bridge testing in our ST20G5 review gives us a very clear picture of the ULi chip's performance and capabilities. You can see our battery of audio and I/O tests starting here, where the Shuttle XPC ST20G5 based on the ULi chip takes on an array of nForce4- and K8T890-based motherboards.
The ULi M1573 puts in a decent showing overall, with solid ATA and SATA transfer rates and audio capabilities that are the class of the field. The M1573's HD Audio implementation combines relatively low CPU utilization with best-of-the-bunch scores for frequency response and total harmonic distortion. Even Geoff's picky ears weren't offended by the ULi audio. This result is especially notable inside of a Shuttle XPC, because we in the past have noted especially high levels of audio interference inside some of Shuttle's toaster-sized boxes.
Unfortunately, the M1573 wasn't all roses. Its USB ports had the lowest transfer rates and highest CPU utilization of the bunch. The ST20G5 also didn't play well at all with its onboard Broadcom PCI Express NIC chip, but that chip hangs off of the ATI RS480 north bridge, not off of the ULi south bridge.
All in all, the ULi south bridge looks like the best option for ATI Radeon Xpress 200-based motherboards right now, and I expect that will remain the case unless and until ATI's upcoming south bridges can prove their worth.