ABIT ZM6 ZX Socket-370

ABIT was all dressed up with no place to go with the BM6, the reason behind this being that ABIT's ultra stable, ultra overclockable BM6 was utterly wasted on one of the most unoverclockable CPU platforms Intel offers currently, the Socket-370 Celeron.  Although the 300MHz PPGA (Socket-370) Celeron apparently functions quite well as a 450MHz performer, the newer 366, 400 and upcoming 433MHz Celeron CPU's are about as overclockable as the old Cyrix 6x86 processors were, meaning that they aren't the world's best overclockers.  So with the ABIT BM6, you were essentially spending $100 on a motherboard whose features were about as useful to you as a heatsink on your BIOS chip. 

ABIT's solution?  A scaled down, albeit not crippled, version of the BM6 based on Intel's "scaled down" version of the BX chipset, the 440ZX.  Rightfully dubbed, the ZM6, ABIT is back with a motherboard that looks virtually identical to the BM6 on the outside, but marches to the beat of a different drummer on the inside with the 440ZX chipset powering the board; and above all, the ZM6 offers you just about everything the BM6 did, with one desired absence, the higher cost of a board whose potential you'll never tap.

New Anand Tech Report Card Rating
89/B+

Do not compare newer ratings to older ones, the newer ratings are much more aggressive

The Good

The ZM6 is perfectly identical, from a layout perspective, to the ABIT BM6 with the only difference being that in place of the 443BX North Bridge controller, ABIT outfitted the ZM6 with the 443ZX North Bridge chip, a difference which will be discussed shortly.  The ZM6 features ABIT's now standard 5/2/1 expansion slot configuration (PCI/ISA/AGP), and just like the BH6 and the BM6, the board features a total of three DIMM slots for memory expansion.

The physical size of the motherboard's PCB is an extremely manageable 12" x 8.3" (30.5cm x 21.0cm) which happens to be the same size as the good ol' ABIT BH6.  The HDD and FDD connectors are placed along the bottom edge of the motherboard, and the Socket-370 interface is crowded by electrolytic capacitors designed to improve the stability of the motherboard.  If you were to judge the motherboard based solely on looks, you could dismiss the ZM6 as being a BM6 look alike and calling it quits.  Fortunately, for ABIT's sake (otherwise this would be one short review) the ZM6 does offer its own set of unique qualities.

The 440ZX chipset is to the 440BX chipset as the 440EX chipset was to the 440LX chipset.  If that last statement made absolutely no sense whatsoever to you then let's work on clarifying the positioning of the 440ZX chipset.  The 440BX chipset contains a few features that some users will never use, one of which happens to be its support for up to 8 rows of memory (4 double-sided DIMMs).   If you look at a standard 16x64 128MB SDRAM DIMM you'll notice that there are physically chips on both sides of the DIMM, as you might be able to guess, that means the DIMM in question is a double-sided DIMM.  At the same time, if you look at a standard 8 x 64 64MB SDRAM DIMM you'll notice that there are chips on only one side of the DIMM, meaning that this particular DIMM would be a single-sided DIMM.  So on a motherboard with the BX chipset, you could theoretically install 8 of the single-sided 64MB DIMMs or 4 of the double-sided 128MB DIMMs.  Before you begin bragging about how you can do that on your motherboard, quietly ask yourself if you'll ever need 512MB of RAM. 

Chances are, unless you're going to be operating a high end workstation or server (in which case you should stop considering a Socket-370 Celeron as a possible processing platform), that you won't reach that 512MB memory limit anytime soon that is provided for by the BX chipset 8 addressable rows of memory.  This is the same BX chipset that is found on the ABIT BM6, now if you're not going to be using that much memory it wouldn't make much sense to be using a chipset that supports a feature you're not going to be using during the lifetime of your computer.   ABIT's solution?  The Intel 440ZX chipset, with 4 addressable rows of memory, you can install 2 double-sided DIMMs or any combination of double and single-sided DIMMs to approach that 4 row memory limitation of the ZX chipset.  Because of the numerous possibilities when installing RAM on a 440ZX based system, ABIT chose to outfit the ZM6 with three DIMM slots capable of accepting either double or single-sided DIMMs, allowing for a user to install 3 single-sided 64MB DIMMs on the ZM6 where they would only be able to install 2 on a standard ZX board with a meager two DIMM slots.  ABIT even claims that, in-lab, they have been able to exceed Intel's specified memory limitation of the ZX chipset by 256MB with two double-sided PC66 Hitachi 256MB SDRAM modules for a total of 512MB of RAM. 

The second, and final difference between the 440ZX and the 440BX chipset lies in the ZX's support for a total of 4 bus master PCI slots in comparison to the BX's support for 5.  In order to cut costs on the ZM6 (since the ZM6 is identical to the BM6 in every way except the presence of the ZX chipset, it is cheaper to build two motherboards out of a similar design that to create a new design for every board) ABIT included a 5th PCI slot without the ability to be run as a bus master PCI peripheral.  While some peripherals do require that they be installed in a PCI master slot, there are a few exceptions such as some PCI graphics accelerators (i.e. Matrox Millennium/Millennium II), 3D accelerators, and some Ethernet adaptors among other devices that don't require the presence of a PCI bus master signal in the slot they're installed in.