Athlon Motherboard Roundup - March 2000

Depending on which chipset (more specifically, what south bridge) is present on the motherboard, the expansion slot possibilities change. 

For motherboards based on the AMD 756 South Bridge, because of the lack of an integrated AC’97/MC’97 controller, there are no possibilities for an AMR slot.   Since the 756 does feature an integrated PCI-ISA bridge, most motherboard manufacturers have had no problem in offering configurations with up to four ISA slots because they essentially come at nothing more than the costs of the slots themselves and the PCB space they take up. 

Other than the relatively new Microstar K7Pro, no motherboard that uses the AMD 756 South Bridge has ever been produced with more than 5 PCI slots.  While it is possible to feature 6 PCI slots, we have yet to see a manufacture other than MSI offer this.  And with the imminent demise of the AMD 750 chipset, don’t expect to see any new AMD 750 based motherboards offer a 6/1/1 (PCI/ISA/AGP) expansion slot configuration.

The VIA 686A South Bridge, featured on all KX133 motherboards and some AMD 750 motherboards, also features an integrated PCI-ISA bridge, making it easier and more appealing for motherboard manufacturers to include ISA slots in their motherboard designs.  While this isn’t exactly the best for the industry as a whole since we’re trying to get away from ISA, it offers a level of flexibility that some users can appreciate, although more and more manufacturers will soon choose to offer ISA slots only as an OEM option. 

The 686A South Bridge also features an integrated AC’97/MC’97 controller which allows for an AMR slot to be present on motherboards that use this South Bridge.  Unfortunately, this means that most KX133 motherboards will feature an AMR slot, which, honestly, isn’t useful to most users.  The AMR standard is directed at OEMs and system integrators that want to keep costs low while offering basic functionality.  The slot is not intended for use as an aftermarket upgrade, which is why you don’t see many AMR modems/audio devices for sale. 

The major downside to this integrated AC’97/MC’97 controller is that motherboard manufacturers will implement an AMR slot on their boards, which could potentially take the position of what would otherwise be an extra PCI slot.  To most AnandTech readers, an extra PCI slot is much more useful than an AMR slot.