The Difference Between SiS 645 And SiS 645DX
Schematic architecture of the SiS 645DX chipset: compared to its predecessor, the SiS 645, only the Northbridge has been replaced.
Last December, we tested the SiS 645 chipset, in a comparison with other chipsets for the Intel Pentium 4. Now, the Taiwanese manufacturer has reworked the memory interface and increased the FSB clock to 133 MHz in preparation for the new Pentium 4's arrival.
All other aspects of the chipset are fully identical - the IDE interfaces continue to work in Ultra-DMA/100 mode, and the USB controller conforms to 1.1 standards. This fact can be determined through the identical Southbridge SiS 961, meaning that Ultra-DMA/133 and USB 2.0 are currently not supported.
An interesting feature set for OEM manufacturers is the graphics, integrated in the Northbridge, which is completely sufficient for simple office applications that involve 2D images. Ambitious users can use a higher-performance graphics card with the AGP slot.
The 6 PCI slots are special features, which also provide full IRQ support. In theory, the memory can be extended to 3 GB, but we can only get clear results on this in a later test with various motherboards. For the entire duration of operation, the Northbridge was notable for its very small increase in temperature, and so, in contrast to products from competitors, it does not require an active cooler.
The manufacturers Asus and MSI plan to come out with SiS 645DX motherboards soon. Asus, for example, will be offering the P4S333.