AOpen AX4B Pro 533 i845E mainboard

Friday, August 02, 2002


The previous generation of this motherboard -- the AX4G Pro -- was based around the "G" series of the Intel i845 chipset, who's only remarkable feature was an integrated graphics card.

The biggest difference between this board and the last, however, is support for DDR333 memory. With the introduction of the AX4G Pro, AOpen's engineers had seen fit to tweak the chipset's settings in order to allow for the 166MHz memory bus required by the DDR333 standard.

To our great surprise, though, AOpen did not include the same functionality in the new AX4B Pro 533 -- it supports only DDR200, and DDR266.

Asides from that, the AX4B Pro 533 differs little from the AX4G Pro. Like the latter, the AX4B Pro 533 includes a 6-channels Realtek ALC 650 audio-card, and a Realtek RTL8100BL 10/100Base-T Ethernet controller.

One major feature that did not make a comeback is the inclusion of an IDE controller capable of supporting ATA133 drives. Unfortunately, AOpen seems to have opted for the Promise Technologies PDC20275 drive controller -- which also lacks support for RAID 0+1 -- rather than the more capable PDC20276.

Finally, it's worth mentioning that the AX4B Pro 533 is backed-up by a sibling -- the AX4B 533 Tube -- which includes a vacuum tube as part of its audio circuitry output, but which comes with three fewer PCI slots. We hope to test the "Tube" version of this mainboard within the next few weeks.

So, without further ado, let's head in to the analysis.

Characteristics of the AOpen AX4B Pro 533
Support for 533 MHz FSB Intel Pentium 4 socket 478 CPUs
Form factor
ATX 30.5cm 24.4cm
6 PCI - 0 ISA - 1 CNR - 1 AGP - 6 USB 2.0
3X 184-pin DIMM sockets DDR SDRAM slots for up to 2GB
of DDR200, DDR266, DDR333.
100Mhz to 248Mhz in 1Mhz increment
Vcore adj.
1.1v to 1.85v in 0.025 increment
VDram - VAGP adj.
Audio chipset
Realtek ALC650


The AOpen AX4B Pro 533's audio circuitry is based around a Realtek ALC650 sound-chip. The ALC650 supports AC3, and 5.1 Surround Sound, and allows users to hook-in up to six audio channels, including a center base channel.

From a fidelity standpoint, the Realtek AL650 is quite good at what it does, and should satisfy most users.

Note that the SPDIF connectors that are required to set-up RCA and optical ports are present on the motherboard, but, unfortunately, the proper cables are not included.


The AOpen AX4B Pro 533 is a Jumperless motherboard. That means no fooling around with jumpers to get your system up and running; the entire set-up routine can be handled from within the BIOS.

The principal BIOS menu is labeled "Frequency/Voltage Control", and is where users will spend most of their time.

The menu includes a number of options, including the ability to set the FSB frequency to between 100Mhz and 248Mhz in 1MHz increments.

Unfortunately, no option is included for modifying the clock multiplier setting.

The Vcore voltage, however, is adjustable, and can be set to any of the values indicated in the table above.

Also, as expected, a number of memory-timing settings can also be tweaked from within the "Advanced Chipset Features" menu. This includes the ability to manually set the memory bus frequency, or to set it to SPD ("Serial Presence Detect"), which allows the system to determine a proper setting automatically.


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