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.

The Good

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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.

AOpen's jumperless CPU configuration is carried over almost directly from the MX64 and the AX63Pro. Like those models, the AX64Pro features the AWARD 4.60PGMA BIOS core, which is a custom AOpen version of the more common 4.51PG. Now that Award has the improved 6.00PG, we'd like to see all manufacturers go ahead and implement it on their boards, including AOpen.

For overclockers, FSB settings of 66 / 75 / 83 / 100 / 103 / 105 / 110 / 112 / 115 / 120 / 124 / 124 / 133 / 140 / 150 are all available in the BIOS. While there are 7 FSB speeds between 100 and 124 MHz, we'd like to see more in the 133 - 150 MHz range, especially with the incredible overclocking ability of the Coppermine core. Clock multiplier is also configured in the BIOS, but since most Slot-1 CPU's today are multiplier-locked, this is almost a moot point.

More importantly, like other "Pro" models from AOpen, the AX64Pro features core voltage adjustments in the BIOS with options from 1.3V - 2.10V in 0.05V increments and 2.10V - 3.50V in 0.1V increments. Seven 2200 uF capacitors sit right behind the Slot-1 interface, with four more located near the memory slots. These 2200 uF capacitors are the same low ESR capacitors found on the AX6BC Pro Gold and potentially contribute to the AX64Pro's solid stability. While the stability of the AX64Pro was excellent, it fell a bit behind the ASUS P3V4X and its i440BX cousin, the AX6BC Pro Gold.

The non-jumperless part of the setup comes when you want to overclock. Two 6-pin jumper blocks determine what frequency range is available in the BIOS, with the option of Auto, 66-83 MHz, 100-124MHz, and 133-150MHz. The Auto setting determines what range of frequencies are available based on the CPU in use and its default speed. The other settings are, of course, intended for overclockers. All AGP and PCI ratios are automatically handled based on the FSB speed range selected via the jumpers or auto detected from the CPU.

With the AX64Pro, AOpen introduces a feature we've seen before from other manufacturers, but never on an AOpen board - a second BIOS flash ROM chip that serves as a backup in case of failure. AOpen likes to call it "Die Hard BIOS," but it operates much like Gigabyte's DualBIOS. The difference is that Gigabyte's solution includes a utility embedded in the BIOS to configure DualBIOS, while AOpen simply has two BIOS chips onboard and a jumper to switch between them. Nevertheless, the security blanket afforded by Die Hard BIOS against failed flashes BIOS attacking viruses is nice.

The BIOS options may come as a bit of a surprise for those that have never used a VIA based board before, as there are a number of options not found on Intel chipset-based systems. The most obvious is the memory setting mentioned above. As with other VIA Apollo Pro 133A boards, the AOpen offers the ability to enable or disable AGP 4X support from the Chipset Features Setup. Interestingly enough, there was no option for enabling/disabling AGP Fast Writes.

Like other Apollo Pro 133/133A boards, the AX64Pro supports an "asynchronous" memory clock, meaning that it can run at a different speed than the FSB. Options include FSB clock and FSB clock +/- 33 MHz. When using the 133 MHz bus, FSB + 33 MHz is not available, nor is FSB - 33MHz when using a 66MHz FSB. It should also be noted that the setting labeled +/- 33 MHz is actually adding or subtracting the PCI bus speed. So if you're running a 150 MHz FSB, with the memory clock set for FSB - 33 MHz, you're actually getting 150 - 37.5 = 112.5 MHz (FSB = 150 MHz, PCI clock = 150/4=37.5 MHz). This is a function of the VIA chipset rather than something unique to AOpen.

One feature that is included on this board, but is still missing on some motherboards, is the ability to configure what the system will do when AC power is restored after a power outage. The system can either remain off, turn on, or resume last power state when power is restored. This is a feature that has often been overlooked since ATX and soft power became available, but is critical for anyone using a system that must be on 24/7 or as close as possible. It also allows for users to shut the system on and off from a surge protector.

The VIA 686A Super South Bridge provides support for integrated hardware monitoring of 5 positive voltages, 3 temperatures, and 2 fan speeds. AOpen chose to monitor only 4 voltages, including Vcore, +12V, +5V, and +3.3V. Temperature is read from the CPU's on-die thermal diode, the 686A chip itself, and from a thermistor header placed next to the DIMM slots. Unfortunately, no such thermistor is included with the board. One fan header is located next to the CPU, while the other is at the front left corner of the board. No hardware monitoring information is shown in the BIOS, but can be read by the included utility or by many of the shareware utilities available on the web.

While AOpen still does not include a printed manual, they've expanded their Easy Installation Guide to a fold out poster that includes all the information you will need to get the system up and running. They even walk you through the installation of VIA's 4-in-1 service pack. A full manual is still included on the CD in PDF format and is more detailed than previous AOpen manuals, which is to say just about everything is covered in this manual. Also on that CD is an OEM copy of Norton Crash Guard and Norton AntiVirus for Windows 9x - not a bad bundle for a motherboard.

The Bad

Our biggest problem with the AX64Pro is with its expansion capabilities. With only 4 PCI slots, the AX64Pro is only slightly ahead of its baby brother, the MX64, which is a microATX board. Consider the fact that the ATX standard support 3 more slots than microATX, and it's clear that there is no good reason for the AX64Pro to be hampered in this manner. Four PCI slots is enough for many users, but for others it's simply unacceptable. Ideally, AOpen would remove the ISA slot and put the AMR slot in that shared position, while adding two more PCI slots for a total of 6. At the very least, they should add a 5th PCI slot since it would not require the removal of anything.

Another disappointment we had with the AX64Pro was the slightly below average performance we encountered when compared to other 133A boards with our benchmark suite. While its only a few percentage points behind the average, it is between 5 and 10 percent slower than the class leaders. The BIOS is still revision 1.00 and the VIA Apollo Pro 133A chipset is sensitive to BIOS tweaks, so we still have hope that performance will improve in the future. For now, the AX64Pro is penalized slightly for this.

It should be noted that, while CPU core voltage adjustments in the BIOS is a great feature for overclocking, the AOpen does allow you to select any voltage, regardless of the CPU installed. This makes it all too easy

USB Compatibility

• Number of Front Universal Serial Bus Root Ports: 2

• Number of Rear Universal Serial Bus Root Ports: 2

• USB IRQ Enable/Disable in BIOS: Yes

• USB Keyboard Support in BIOS: Yes

Recommended SDRAM

Recommended SDRAM: 1 x 128MB Corsair PC133 SDRAM; 1 x 128MB Mushkin PC133 SDRAM

SDRAM Tested: 1 x 128MB Corsair PC133 SDRAM; 1 x 128MB Mushkin PC133 SDRAM

Manufacturer: Corsair
Purchase Website: http://www.corsairmicro.com

Manufacturer: Mushkin
Purchase Website: http://www.mushkin.com

The Test

In recent times, choosing a motherboard cannot be completely determined by a Winstone score. Now, many boards come within one Winstone point of each other and therefore the need to benchmark boards against each other falls. Therefore you shouldn't base your decision entirely on the benchmarks you see here, but also on the technical features and advantages of this particular board, seeing as that will probably make the greatest difference in your overall experience.

Click Here to learn about AnandTech's Motherboard Testing Methodology.

If the limitation of 4 PCI slots doesn't bother you, the AX64Pro is a very good VIA Apollo Pro 133A solution. If AOpen would take this design, add a PCI slot or two, put in some more FSB settings, and tweak the BIOS, they would clearly have the best VIA 133A board on the market. For now, we'll have to live with the "merely" very good AX64Pro.

How it Rates