ABIT KA7 KX133 Slot-A ATX

The KA7 features a total of four DIMM slots that take advantage of the 371's PC133/VC133 SDRAM support as well as its PC100/VC100 SDRAM support. If you think about it, most Athlon motherboards feature only 3 DIMM slots and have refrained from adding a fourth slot. There are a number of reasons for this, among the top of the list is the fact that it costs more to add a fourth slot, and it oftentimes goes unused because of the ever increasing SDRAM module densities. VIA's PC133 SDRAM specification also calls for a limit of 1.5GB of PC133 SDRAM on a motherboard using their DRAM controller, meaning that based on today's SDRAM densities, three 512MB PC133 SDRAM modules would be the maximum that should be installed in any PC133 compliant VIA based motherboard, giving most motherboard manufacturers another reason to drop that fourth DIMM slot.

ABIT chose to take the path less traveled, and while it may not make all of the difference in the world, the fact that there is an extra DIMM slot on board could potentially allow those of you with oversized heatsinks to still have two available DIMM slots even after your heatsink extends over the first two banks, right? Wrong. Unfortunately, there is one capacitor that happens to be in the way of any heatsink attempting to extend over the memory banks.

In case you do use all four DIMM slots, ABIT has included their 6-chip Texas Instrument memory buffer, present between the 371 North Bridge and the memory banks themselves in order to improve stability. This same "feature" was present on the original BX6, and, while we originally took the feature for granted and assumed that it actually did something, we eventually came to the conclusion that although it may cause some positive effect on the stability of a motherboard under heavy memory load (all four banks populated) the difference isn't really noticeable and is more of a "just in case" on ABIT's part rather than a guaranteed solution to a problem.

Regardless, the memory buffer is not really hurting you by being there other than driving the cost of the board up slightly. But if history repeats itself, we will see a successor to the KA7 built on a smaller PCB, without that fourth DIMM slot and without the 6-chip external memory buffer in the not-so-distant future.

Unlike ABIT's first VIA based solution, the KA7 uses VIA's 686A South Bridge, which in the case of this board actually makes quite a bit of sense. The 686A South Bridge integrates a PCI-ISA bridge (in order to support ISA slots), hardware monitoring, and an I/O controller all into that one South Bridge chip. Since the KA7 takes advantage of hardware monitoring (external thermistor headers are present on the motherboard) and features a single ISA slot for those users that have the one component they just can't get rid of yet, by integrating hardware monitoring and an ISA bridge into the 686A chip, ABIT can keep the cost of the board at a more reasonable level.

The 686A South Bridge also offers an integrated AC/MC'97 controller for use with on-board audio codecs and/or an AMR slot. Unlike just about every other motherboard manufacturer out there, ABIT (as well as Tyan) refused to outfit the KA7 with an AMR slot thus leaving enough space for their 6/1/1 expansion slot layout (PCI/ISA/AGP). While this will make the KA7 take a back seat to ASUS' K7V and K7V-RM solutions in the minds of system integrators and OEMs that are interested in that AMR slot, for most PC enthusiasts and do-it-yourselfers, not having an AMR slot on the KA7 is a blessing.

The KA7 joins the Tyan Trinity K7 as the only other KX133 motherboard we've tested at the time of publication that features 6 PCI slots. Of the 6 PCI slots, all but one (the shared one) are capable of accepting full length cards, and although the shared slot isn't capable of accepting a full length card, the ISA slot it is shared with is able to accept a full length ISA peripheral.

With so many PCI slots, it is always helpful to know what IRQs are shared among what slots on the board itself. The sharing pattern is actually pretty standard for any motherboard outfitted with 6 PCI slots. The AGP slot can actually share an IRQ with either the first or the second PCI slot. If the first PCI slot is occupied and the second isn't, the AGP slot will attempt to share the IRQ of the second PCI slot and vice versa. The 3rd and 6th PCI slots share an IRQ as do the 4th and 5th slots. The 4th and 5th slots also share an IRQ with the on-board USB controller. Since most PCI devices work just fine while sharing an IRQ, this shouldn't cause any trouble. This is actually pretty standard from one motherboard to the next; unfortunately, it isn't a very well documented reality.

ABIT decided to go completely against the grain with the KA7 and didn't even bother to include an on-board audio codec for CPU driven sound. Once again, the KA7 loses to the K7V and K7V-RM in the eyes of system integrators and OEMs but wins in the eyes of hardware enthusiasts that never wanted those "features" there in the first place.

While the KA7 didn't turn out to be as stable as the K7V, the most stable KX133 motherboard we've tested to date, the board actually managed to impress us quite a bit. The KA7 is quite possibly the most stable ABIT motherboard we've tested to date; it had no problem completing our stability tests with more than just flying colors, and although it wasn't the best, it was definitely above average in terms of how reliably the board ran during our extensive testing period.