Well, it looks as if the recent tendency to improve the performance of the chipsets has also touched SiS Company. Although, unlike VIA, they behaved a bit more modest and avoided excessive pomposity: no special press-releases, no "pseudo-new" chipsets with additional indexes. In reality everything is much simpler: SiS started shipping the new SiS645 chipset revision with A2 index. We learned about it when Soltek announced the launching of their updated SL-85DRS mainboard on SiS645.

In fact, the exterior of SL-85DRS2 and SL-85DRS is nearly identical. All the difference lies with the chipset revision and the mainboard name:

The other mainboard specs remained the same. The mainboard is designed in ATX form-factor, supports Socket478 Pentium 4 CPUs, features 3 DIMM slots for up to 3GB PC2100/PC1600 or 2Gb PC2700 DDR SDRAM. Besides, there are 6 PCI slots AGP 4x, AC’97 audio and 4 USB ports. The mainboard features MuTIOL bus and an additional 12V ATX 2.03 connector. As for overclocking friendly features, SL-85DRS allows adjusting the clock frequency multiplier, Vcore and FSB frequency via BIOS Setup due to RedStorm overclocking technology.
It is not clear so far, how greatly increased the performance of the new SiS645 (A2) chipset revision compared with the previous A1 revision. However, as we remember, the old chipset revision was really fast especially when working with PC2700 DDR SDRAM (see our article called SiS645 Chipset: DDR333 for Pentium 4 Platforms). So, now SiS645 has everything necessary to become an indisputable performance leader among all existing Pentium 4 chipsets. Note that SiS managed to avoid possible negative reaction of the customers like the one, which emerged after the launching of KT266A or VIA P4X266A...