Verdict: Shuttle adds CrossFire and the X38 chipset to our favourite shoebox PC.
In much the same way as adhesive tape is referred to as Sellotape, Shuttle has become the synonym for any small form factor PC. This isn't surprising when you consider that Shuttle was the first company to popularise the format, and therefore it's Shuttle that most people turn to for a portable gaming system or space-saving office PC - probably because they tend to be quite good.
If this SFF bare bones kit looks familiar, it's because the SX38P2 Pro uses the same brilliant chassis as the last award-winning Shuttle kit we reviewed, the SP35P2 Pro. The Lilliputian Shuttle motherboard and PSU have been upgraded but are still housed in the same sleek and moody-looking case, ready for your own full-sized components.
As usual, the intricate internal layout is as well designed as it is small, efficiently making use of every last inch of space. The cooling setup is also well designed, with the main airflow directed through the case by the relatively large 70mm, 82mm and 90mm fans of the CPU cooler and PSU. A pair of smaller 60mm fans prevents any heat pooling in the roof of the case. You can squeeze an impressive amount of kit inside the diminutive case. Two hard disk caddies are suspended near the roof of the case, and a third S-ATA disk can be added underneath the 5.25in drive bay instead of a floppy drive.
The most obvious upgrade over the SP35P2 Pro (on paper, at least) is the motherboard chipset: this new SX38P2 Pro is based around Intel's X38 Northbridge rather than the cheaper P35 chipset. It's clear that Shuttle knows exactly who it's targeting with the new Northbridge; the company's website speaks of 'maximum overclocking' and 'hard-core gaming' as much as space saving and ergonomics.
New technology usually results in a higher price - the P35-based SP35P2 Pro cost only £321, but this update costs little more. Still, as the previous model was so accomplished, handling a large dual-slot graphics card and overclocking our CPU to its air-cooled limit, the SX38P2 Pro had better be good.
Unlike the P35, the X38 chipset features PCI-E 2.0 support, providing double the bandwidth of PCI-E 1.1. The X38 chip also has a gazillion PCI-E lanes (well, 32), so both PCI-E slots are supplied with the full 16 lanes for full-speed PCI-E 2.0 CrossFire. In comparison, the SP35P2 Pro has only one graphics slot. The four DDR2 memory sockets allow you to install up to 8GB of memory, and there's even enough space to squeeze in the heatsinks of Corsair's Dominator memory.
Another upgrade over the SP35P2 Pro is the PSU. It may only be a 50W bump from 400W to 450W, but given that you might be using two high-performance cards, it's a welcome addition. Bizarrely, it has only one PCI-E power connector; if you want to use a power-hungry graphics setup, you'll need to use the PSU's two Molex plugs of the PSU with a PCI-E converter. Unfortunately this will leave you with only three S-ATA power connectors to run your optical drive and hard disks.
As there's only room for two expansion slots, and both are 16x PCI-E, you're restricted to PCI-E expansion cards. This could be an issue if you'd rather have a sound card than a second graphics card, although the 8-channel Intel HD on-board audio is fine and provides both digital and optical S/PDIF. Also bear in mind that the two 16x graphics slots are placed close together, so only single-height cards can be used in CrossFire.
Performance
We'd expect a laptop to return slightly sluggish results in our Media Benchmarks, but an SFF PC has less room to hide. The motherboard inside may be diddy, but it should be capable of producing roughly the same performance as an equivalent ATX board.
A score of 957 is a little short of the mark in our image editing test, but the Shuttle quickly redeemed itself with a capable 1,016 in video editing. Our multitasking test proved to be a little tougher, with a score of 739 dragging down the overall score to a below-par 904. This result would place the Shuttle near the bottom of the pack among the full-sized ATX motherboards in our motherboard Labs test.
When it comes to separating the wheat from the chaff, though, there's nothing quite like overclocking. Overclocking is a particularly tough task for an SFF PC, as the motherboard will have a cramped layout, the cooling in the small case will have to deal with increased heat and there's a smaller than usual power supply unit that has to provide a greater amount of voltage. Nevertheless, when a manufacturer claims that a product provides 'maximum overclocking' then that's exactly what we expect.
First off, we decided to determine the motherboard's maximum FSB. It remained stable up to 480MHz, but refused to boot at 490MHz. Nevertheless, this is more than enough to push our CPU as far as it will go without needing buckets of water or LN2.
Overvolting a CPU is necessary for it to hit the highest clock speeds, but substantially increases the amount of waste heat it produces. When increasing the CPU voltage to 1.525V, the Shuttle's case fans increased in speed and volume as things became toasty inside the small case. However, the system was perfectly stable, and the extra voltage allowed us to push the FSB to 458MHz (1,832MHz effective), overclocking our CPU from 2.66GHz up to 3.66GHz. This may only leave 22MHz of FSB headroom if you own a more overclockable CPU but, unless you can mod a liquid-cooling loop into the case, this probably won't be a big issue.
The Shuttle's overclocked scores are much more impressive than the stock results, increasing the photo editing score to a strong 1,321, while video editing soared to 1,357. Both scores are only 20 points or so lower than those of the Asus Maximus Extreme, which is a £200 X38-based ATX motherboard specifically made for big overclocks and performance. Again, multitasking dragged down the scores slightly, but 1,242 is still a fast overall result. However, this score is only three points higher than the P35-based Shuttle SP35P2 Pro's score, so the X38 chipset brings no benefits in terms of raw performance.
Unfortunately, Shuttle has told us that it was discontinuing the XPS SP35P2 Pro in favour of a plain SP35P2. However, the company assures us that 'just its Pro features are being dropped - the fingerprint reader and the Speed Link function of the USB jack on the front. Everything else stays the same'. This should mean that the BIOS will continue to support the big overclock that we managed with the SP35P2 Pro, but we can't be absolutely sure without testing the new version.
Conclusion
The P35-based Shuttle XPC SP35P2 Pro walked away with a Custom PC Premium Grade award last December, and the X38-based Shuttle SX38P2 Pro offers a few valuable extras. PCI-E 2.0 support is present in many new graphics cards so that's a useful extra, while full-speed, dual 16-lane CrossFire might also appeal, epsecially as the PSU has more power to give. Performance is also on a par with that of the soon to be retired SP35P2 Pro, as are its overclocking abilities.
However, these relatively minor improvements mean that the SX38P2 Pro is £120 more expensive, and therefore hard to recommend. Buy the SX35P2 Pro while you still can.
