AOpen XC Cube MZ855-II

Verdict: Its excellent overclocking capabilities and the neat performance of the Pentium M architecture are somewhat thwarted by the fact that the MZ855-II is so lacking in terms of graphics potential

Small form factor systems are far too big. During the time when most desktop PCs were beige monstrosities, a toaster-sized SFF was refreshingly dinky, but these days, tiny is the new black. You could quite easily pound a Mac Mini into pate using a Shuttle, such is the size disparity between the two. Small form factor PCs need to slim down to fight the new Mac menace, and the first contender into the ring is AOpen.

The XC Cube design has been put through rigorous training, and as a result, it has lost half its bulk. The MZ855-II is literally half the height of a traditional SFF, but still offers much of the same flexibility.

The MZ855-II has only had its height reduced during its trimming down, so its footprint remains the same as that of a regular SFF. As a result, it doesn't need some kind of Speedo-sized motherboard, instead making do with the UX855GME Pentium M motherboard, which is also used in the full-size EY855 XC Cube. As the MZ855-II isn't very tall, the AGP 4x and PCI slot on the motherboard are limited to half-height expansion cards. There's room inside the diminutive chassis for just a single 3.5in hard disk and the optical bay is of the laptop variety. This will increase your build cost a little, as a dual-layer DVD burner for a laptop will cost about £100.

If you do hanker for more drives, AOpen has made an expansion box called the MZ850e, which contains two full-sized 5.25in bays, one of which can accommodate two 3.5in hard disks instead, plus two additional USB 2 ports. The MZ850e is designed to sit on top of the main chassis, but it rather confuses the point of the MZ855-II to have an expansion unit on top of it, as this jacks the system back to full SFF height.

However, lack of storage bays is par for the course with any SFF system, and with 300GB and 400GB hard disks now available, it isn't too big an issue unless you're the kind of massive file leech who is responsible for forcing Jennifer Lopez to start buying jewellery at Argos. No, the biggest drawback of the MZ855-II for the discerning Custom PC reader is the chipset. AOpen's first Pentium M desktop board was based on the Intel 855GME, but that was nearly six months ago: the company's most recent full-size Pentium M motherboard, the i915GMm-HFS was based on the much more impressive Intel 915GM chipset. It's disappointing then that the MZ855-II uses the older 855GME chipset, which lacks modern features. For example, the chipset only supports Pentium Ms with a 400MHz FSB. It also isn't a PCI-E chipset, and only integrates Intel's Extreme Graphics 2, rather than the almost acceptable Graphics Media Accelerator 900 available with the 915GM.

Building the MZ855-II is a little more involved than it is with some XC Cubes. An H-shaped chassis crossbar on the top has to be unscrewed and lifted out before you can fit the major interior components. However, this is permanently attached to the power cabling and houses some regulation circuitry, so it must be left dangling during construction.

To conserve interior space, AOpen has taken the PSU out and housed it in an external power brick. It's only a 150W unit, but this is fine for a Pentium M system with limited upgrade potential, and means that it's capable of running without a fan.

You'll also need to remove and unclip the front drive cage to install RAM and drives. Installing the CPU is made a little more fiddly than necessary by the temperature sensor. This sticks up from the middle of the slot, and pushes the processor out of its socket until you secure it with Pentium M's novel screw system. Once you've done this, though, the heatsink clips on easily.

The CPU is the only part of the MZ855-II that isn't passively cooled, and the 70mm fan on the bundled heatsink is remarkably silent, too. In fact, AOpen claims the MZ855 itself only produces 22dB of noise even at full load, which is less than the average hard disk. Just the latter and the optical drive will add to the noise, and any half-height graphics card is also likely to be passively cooled. The only way to build a quieter PC would be to use a completely passively cooled model, such as an EPIA-based Tranquil or Hush.

Despite its small size, the MZ855-II still offers a decent complement of ports. On the back you can find serial and parallel ports, plus two USB 2, FireWire, Ethernet and VGA. The 6-channel AC97 sound is served up by either a coaxial S/PDIF output or a trio of analogue ports, but audio quality is merely average.

The front fascia also houses a full complement of ports, including both 6- and 4-pin FireWire, plus an optical S/PDIF output as well as headphone and microphone jacks. There's a memory card reader too, which manages to pack support for every important format into just two slots. All of these connections are hidden under two subtle magnetic flaps.

PERFORMANCE

We tested the AOpen with our usual combination of a 1.6GHz Pentium M and 1GB of Corsair XMS 4400 RAM. Although the system's overall score of 0.97 in our Media Benchmarks was nothing to write home about, when you consider that our reference system is a Pentium 4 PC running 1GHz faster, you can really appreciate the potency of the Pentium M. The results were also almost identical to the i915GMm-HFS, showing that you don't lose any performance by using an older chipset.

Overclocking revealed that a pumped-up Pentium M has plenty of power. We managed to raise the FSB from 100MHz to 138MHz, yielding a 38 per cent increase in processor speed to 2.2GHz, which resulted in an almost identical increase in 2D performance. The improvements were fairly evenly felt across all three of our Media Benchmark tests, too.

The best implication of this, however, is that the MZ855-II should be fine with a 533MHz FSB Pentium M, even though its chipset doesn't officially support it.

However, the AOpen's excellent 2D results weren't replicated in the third dimension. With only Intel Extreme Graphics 2 integrated, games from the last millennium are likely to have a tough time, never mind games from last year. If you want to explore some of the most influential PC games from the early 1990s, this is the system on which to do it because, with the low-profile AGP slot, you can't improve much on this by adding a more powerful graphics card.

CONCLUSION

Adding a low-profile digital TV tuner would turn the MZ855-II into a tiny, good-looking and extremely quiet HTPC. It would also make a great office system for the power- and space-conscious. Even a tiny home server wouldn't be out of the question. However, its excellent overclocking capabilities and the neat performance of the Pentium M architecture are somewhat thwarted by the fact that the MZ855-II is so lacking in terms of graphics potential. If your needs fit into the first three of these categories then the AOpen is a Mac Mini beater.

However, anyone hoping to show the Pentium M's amazing gaming potential will have to put their aspirations of miniaturisation to one side and opt for something a bit chunkier.