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Date |
: Apr 24th, 2002 |
| Category |
: Motherboards |
| Manufacturer |
: AOpen |
| Author |
: Jin-Wei Tioh |
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Intel's highly anticipated i845D chipset is essentially the same chipset as the i845, but with DDR capability allowed to be utilized. Being a two chip solution, it consists of the i82845 MCH (Memory Controller Hub) and the i82801BA ICH2 (I/O Controller Hub). The i82845 MCH supports either PC133, DDR200 or DDR266 memory, as well as asynchronous memory bus and FSB operation for PC133 and DDR266 support. The i82801BA is a carry-over from i850, i815 and i810 chipsets, which accounts for the reason why the feature set of the i845 seems a little dated (as compared to the SiS645); only 2 USB host controllers (4 USB ports) and Ultra ATA-100 support. AOpen opted for a massive silver heatsink to dissipate heat from the MCH. While an active cooling solution would definitely be preferable, the MCH did not get very warm during our evaluations.
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As with other AOpen motherboards, the AX4B Pro comes outfitted with a universal AGP slot. A locking mechanism at the end of slot helps secure the AGP card in place. It is basically a small plastic clip, working similarly to that of a DIMM slot by clipping onto the small tab on the AGP card. While it would take quite an amount of force to unseat the AGP card (an amount that would likely have damaged other components more severely), it is a small, but welcome feature.
AOpen is one of the few manufacturers who went above and beyond Intel's specifications to outfit their 845 DDR motherboard with 3 DDR DIMM slots. Although the chipset memory limitation of 2GB still applies, memory expansion is much more convenient as 1GB DDR DIMMs are not easy to come by. For expansion slots, AOpen chose to go with the more OEM oriented 1/5/0/1 (AGP/PCI/ISA/CNR) configuration, something which MSI also decided to do on the MSI 845 Ultra-ARU. Only the last two PCI slots are capable of accommodating full-length cards due to the placement of the IDE and floppy headers.
12 2200uF, 4 1500uF, 6 1100uF, and a bunch of smaller capacitors. 6 voltage regulators sit adjacent to the CPU socket. AOpen utilizes a greater number of lower capacitance low ESR (equivalent series resistance) capacitors. Hence, while the total capacitance may be the same, it is distributed more evenly throughout the motherboard. To further enhance stability, the AX4B Pro was designed with the "Frequency Isolation Wall". This was previously described in our AK77 Plus and AK73 Pro(A) articles, but we'll repeat ourselves here. AOpen attempts to separate the motherboard into regions, where each region is running at similar local frequencies. This serves to minimize signal interference via cross talk which is an unavoidable occurrance in electronic circuits. They also took the pains in calculating the trace lengths and routing to ensure that traces operating at the similar clocks have equivalent lengths, minimizing clock skew.
In the overclocking department, the AX4B Pro is fully jumperless. FSB is adjustable in 1MHz increments via the BIOS, with the clock generator being capable of an astonishing 248MHz! CPU core voltage is similarly jumperless, allowing adjustments from 1.1V to 1.85V in 0.25V increments. Being an Intel CPU, the Pentium 4 is multiplier-locked. VIO and DIMM voltage adjustments are absent. How this will affect the AX4B Pro's overclockability remains to be seen. All 3-pin fan headers held up well when loaded with a black-label Delta fan.
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