Long-time AnandTech readers will know that there hasn't been a manufacturer that has received more AnandTech Editor's Choice Awards than AOpen in the past couple of years. AOpen has consistently been able to deliver the features users demand from a motherboard while maintaining a respectable level of stability through their excellent choice in components as well as their extremely rigorous QA testing procedures that take place before you even set your hands on one of their motherboards.

It is for this reason that every time a new motherboard is announced by AOpen, we eagerly await its arrival in the lab. Their first board based on the VIA Apollo Pro 133A chipset, the MX64, was a great microATX board. Unfortunately, microATX is not the ideal solution for many AnandTech readers simply because of the expansion constraints. Fortunately, AOpen is back with a full ATX Apollo Pro 133A solution, the AX64Pro, which is a member of AOpen's "Pro" line of motherboards that have already garnered two Editor's Choice Awards at AnandTech. Let's see if the AX64Pro will be the third in that line to do so.

Motherboard Specifications

CPU Interface
VIA Apollo Pro 133A
VIA 694X North Bridge
VIA 686A South Bridge
L2 Cache
N/A (on-chip)
Form Factor
Bus Speeds
66 / 75 / 83
100 / 103 / 105 / 110 / 112 / 115 / 120 / 124
124 / 133 / 140 / 150
Voltages Supported
1.3V - 2.10V (in 0.05V increments)
2.10V - 3.50V (in 0.1V increments)
Memory Slots
3 168-pin DIMM Slots
Expansion Slots
1 AMR Slot
1 AGP Slot
4 PCI Slots (4 Full Length)
1 ISA Slot (1 Shared / 0 Full Length)
Onboard Sound
AD1881 AC'97 Audio

The Good

The first thing you notice about the AOpen AX64Pro is the shiny gold plated heatsink that sits atop the 694X North Bridge, the heart of the VIA 133A chipset. It's the same heatsink that adorns the i443BX North Bridge on the AnandTech Editor's Choice winner AX6BC Pro Gold. Our thoughts on the gold heatsink are the same as they were back then - supposedly implemented to help conduct heat in a more efficient manner, the new heatsink does little more than make the motherboard more attractive. Our experience with the 694X North Bridge shows that heat is generally not an issue, as many manufacturers have forgone the heatsink completely. As with AOpen's other flag ship boards, the heatsink is an added touch that doesn't really hurt anything.

The 694X North Bridge is the chip that actually provides the advanced features promised by the VIA Apollo Pro 133A chipset, including AGP 4X support and official 133 MHz front side bus with an SDRAM interface. Our sample featured the updated AGP 4X core that's available on the CE revision of the 694X. The updated stepping of the AGP core eliminates all problems with running graphics accelerators in AGP 4X mode, an issue which plagued some of the first AGP 4X boards based on VIA's chipsets but, because of the updated core, are not present on the AX64Pro. All VIA 133A boards, including that AX64Pro, that are in the channel now should feature the CE revision of the 694X.

The VIA 686A Super South Bridge provides the other half of the Apollo Pro 133A chipset on the AX64Pro. The 686A integrates a dual channel Ultra ATA 66 controller, a PCI-ISA bridge, two USB root hubs (supporting 4 ports total), a Super I/O controller, and hardware monitoring support. Two of those USB ports are located in the standard location, while an internal cable runs to a bracket with a second set of USB ports. With a little ingenuity, they could easily be mounted anywhere else in the case, such as on the front panel.

For full details on the Apollo Pro 133A chipset, see our recent VIA Apollo Pro 133/133A Motherboard Roundup and our first look at the VIA Apollo Pro 133A.

The other feature of the 686A that's not quite so popular among end users, but very popular among OEM's, is its support for AC97 audio and an Audio Modem Riser (AMR). AOpen has taken advantage of these features on the AX64Pro by integrating Analog Devices AD1881 AC97 Audio CODEC and an AMR slot. The AC97 audio will get you by if you just want basic Windows sound feedback, but anyone serious about audio or interested in gaming will definitely want to add a dedicated PCI sound card. Fortunately, the CODEC adds virtually nothing to the cost of the board and, as such, will be a standard feature on all AX64Pro's as well as most other upcoming motherboards. The AC97 audio can be disabled by a jumper.

The 4/1/1/1 (PCI/ISA/AGP/AMR) slot configuration is relatively weak in today's market, especially after we've started seeing numerous boards with 6 PCI slots. In fact, there is actually room on the board for an additional PCI slot without giving anything up and still complying with the ATX specification. Ideally, we'd actually prefer to see either the AMR slot take the place of the ISA slot or be removed completely, allowing physical space for 6 PCI slots total, which the Apollo Pro 133A does support. All four PCI slots are full length, but the sole ISA slot is blocked by front panel I/O connections. There is the chance that a full length AGP card may be blocked by the HDD connectors, but most standard video cards should be fine. Otherwise, everything is laid out beautifully with the ATX power connector out of the way and all HDD/FDD located at the front of the board. We're glad AOpen finally figured out the right location for that FDD connector ;)

A universal AGP slot, which isn't keyed specifically for AGP 2X or AGP 4X cards, lets the user install virtually any currently available AGP card in the slot, whether it is an AGP 1X/2X or 4X card. The AMR slot is placed to the left of the AGP slot, so for those not planning to take advantage of AMR, you'll at least have additional space in front of your video card, potentially allowing exotic cooling methods to be applied (yes, we know you guys are out there ;).

Memory support is provided by 3 DIMM slots sandwiched right up next to the VIA 694X North Bridge, which can hold up to 1.5GB of SDRAM. The slots themselves are capable of accepting PC100 or PC133 SDRAM as well as VC100 or VC133 Virtual Channel SDRAM. With the latter two being little more than vaporware in the market right now, PC100/PC133 memory is really what you can expect to use with the board. The proximity of those DIMM slots may prevent the use of some larger heatsinks, but most users should be just fine.

More Good

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