AGP, IDE-Controller, Memory Interface
The last comprehensive motherboard review was the BX motherboard comparison in fall 1998 . Some things happened on the stage, which I want to illuminate.
Intel's 82440BX chipset was the first one featuring AGP 2x. At 66 MHz, the AGP bus is able to transport 533 MByte/s. Even today this seems to be enough, but games coming with large texture scenes and professional 3D-applications require more bandwidth. That's why the faster AGP 4x has become standard today, making it possible to move up to 1066 MByte/s from the main memory to the graphics board. The BX chipset was never meant to be used at 133 MHz FSB, thus it cannot provide the AGP divisor 1/2 to get the required 66 MHz AGP clock. Your graphics card will have to cope with 88 MHz AGP clock - which is tolerated by only a few models .
VIA's VT82C693A chipset does not support AGP 4x (only 2x, just like BX), no matter what others may want to make you believe. You will have to get a motherboard with the VIA Apollo Pro 133A (VT82C694x) to have full support for AGP 4x and AGP Fast Writes.
The connector of graphics card for AGP 2x has only one nick...
...while all graphics cards supporting AGP 4x can be identified by the second nick.
The South Bridge of Intel's 440BX chipset (82371EB) hosts an UltraDMA/33 controller providing the common two ports. Its performance might be just about fast enough for today's hard discs (modern drives do hardly achieve 30 MByte/s), but all hard drives have their own cache memory, which can be only some kiloBytes or up to 2 MBytes. The memory chips for this kind of cache naturally are much faster than the physical media, providing data rates of many dozen MBytes/s. The 'ICH' of Intel's i8xx chipsets and both VIA South Bridges include an UltraDMA/66 controller. Obviously there are two reasons that makes such an interface interesting today: Better peak performance for hard disc drives with large cache memory and of course future disc drives, which offer a physical bandwidth that surpasses the 33 MB/s
Our latest platform comparison shows clearly that Intel's 440BX is - overclocked to 133 MHz - still the king of SDRAM performance (Showdown at 133 MHz, Part 2) and thus currently the king of memory performance altogether. VIA's 694X chipset is the first non-Intel chipset providing good memory performance, but still not good enough to beat the two years old Intel chipset at the same clock speed. Please don't forget however that BX is only a real alternative for advanced users, since the chipset has not been designed for 133 MHz FSB and it takes some fiddling to make it run at that speed.