The AOpen UX4SG-1394 mainboard uses the ICH5 chip as the South Bridge. It supports two ATA-100 channels, two SerialATA-150 channels (without RAID support, as you simply cannot get two hard drives into the “cube” at a time) and six USB 2.0 ports. Again, the XCcube EZ65 uses only four ports of the six supported; the remaining two ports are implemented as onboard connectors. As for other onboard things, we have three fan connectors, only one of which is actually used for the CPU cooler.
The rest of the mainboard’s functionality is provided by extra onboard chips. Thus, the manufacturer offers Gigabit Ethernet by using a PCI controller from Broadcom instead of the CSA bus. A FireWire controller from Agere works with the three FireWire ports, while the six-channel sound (together with SPDIF inputs and outputs) is implemented via an AC’97 ALC650 codec from Realtek. I think the decision not to use the CSA bus for the network controller could have been caused by financial (licensing) issues. As for the AC’97 codec, it is not new and doesn’t support the AC’97 specification revision 2.3, but it does provide acceptable sound quality.
The PCB layout of the AOpen UX4SG-1394 has a lot to do with the fact that it is used in the XCcube system. Nearly all the components and connectors onboard are conveniently placed and don’t make you show a sleight-of-hands performance when assembling the system. You may only have some difficulty with the ATA/100 connectors (when the system has been already assembled). The Clear CMOS jumper is present and sits in an easily accessible location, like most of the onboard connectors.
Speaking about the functionality, I cannot leave the BIOS aside. Barebone systems are developing fast and their BIOS Setup programs become ever more complex. First barebones to enter the market offered no options for fine-tuning the system or overclocking it. Now we see the situation changing for the better. The BIOS of the AOpen XCcube EZ65 is a definite evidence of the improvements.
So, it is the first time we see a barebone offering CPU overclocking options. The AOpen XCcube EZ65 allows changing the FSB frequency from 100 to 400MHz as well as adjusting the voltages of the CPU, memory and AGP port. The Vcore is adjustable in a range from 1.1V to 1.85V with 0.02V increment. The Vmem can be set from 2.6V to 2.775V, while the Vagp can be boosted to 1.85V. Of course, the mainboard also allows you to change the key memory timings and memory frequency manually. On the other hand, this is still not enough for the poor overclocker to be happy. The overclocking options of the BIOS Setup lack one important thing: an option to fix the PCI/AGP bus frequency. As a result, the AGP/PCI frequency depends on the FSB frequency and is set by a divisor that is determined by the nominal FSB frequency for the processor you use. The frequency of the AGP bus is set as FSB/1.5 for CPUs with 400MHz FSB, as FSB/2 for CPUs with 533MHz FSB and as FSB/3 for the newest CPUs with 800MHz FSB. This fact makes it impossible to overclock processors at your wish. However, the AOpen XCcube EZ65 allows speeding up your processor by 5-10% above the nominal.