Verdict: An XPC that supports quad-core CPUs, but the 975X chipset is a poor choice
The last small form factor bare bones kit we looked at was AOpen's XC Cube EU965. While it offers decent application performance at a good price, with only a 275W PSU and room for a single-slot PCI-E graphics card, it isn't a truly convincing home for a gaming system. Add to this its plain, plasticky looks and it just isn't appealing.
The XPC SD39P2 is Shuttle's idea of what a great, high-end LGA775 SFF bare bones kit should be. On the downside, it's much pricier than the AOpen but, as soon as you remove it from the packaging, it's easy to see why. The build quality and finish of Shuttle's P2 chassis is superb. The smooth, stern aluminium fascia may be too moody for some tastes, but the clean lines and brushed metal drive bay covers are, in our opinion, far superior to the AOpen's flimsy plastic fascia.
Shuttle's P2 case is bigger than its classic designs and other SFFs, and wider and taller the AOpen's case by 2cm. The extra space has been put to good use. It allows Shuttle to fit four DDR2 slots onto the SD39P2's custom motherboard, double that of the AOpen, and there's room for a dual-slot graphics card, since the16x PCI-E slot is set back from the side of the case. While the P2 case is bigger than many SFFs, it's still compact enough to carry under your arm and small enough not to hog all your desk space. The Shuttle also easily wins out in terms of power, with the 400W PSU inside the SD39P2 outgunning the modest 275W model found inside the AOpen.
We've seen several versions of this Shuttle before, in both Socket AM2 and LGA775 incarnations, such as the similarly named and specced Shuttle SD37P2, so we were familiar with its layout. If you don't want to use the single externally accessible 3.5in drive bay for a floppy drive or a media card reader, you can use it to house a hard disk. This means that there would be enough room inside the Shuttle for three hard disks in addition to an optical drive, with the two other 3.5in hard disks stored in removable trays in the roof of the case. As there are four internal S-ATA II ports, all of these drives can be S-ATA. However, bear in mind that Shuttle's motherboard has one EIDE connector, so it can only support two EIDE devices. The routeing of the wire makes it clear that Shuttle intends the EIDE device to be an optical drive and not a hard disk.
Two fans, one 70mm and one 92mm, operate in a push/pull setup to drag in air between the fins of a small aluminium heatpipe-assisted CPU cooler, and then expel it out the right-hand side of the case. In addition to these fans, there are two 60mm fans drawing in cool air at the back of the case in an attempt to create airflow at the top of the case, where the hard disks sit, while the PSU has its own fan. As the SD39P2 is an SFF, however, luxuries such as 120mm fans are out of the question; as is usually the case with an SFF system, you should be prepared for your components to run hotter than they would in a system housed in a breezy midi-tower. Promisingly, though - and unlike the SD37P2 - the SD39P2 has a vent on the top left-hand side of the case, as well as a mount for a 40mm fan, so you can increase its cooling power if you want to be doubly sure that your system won't cook half-way through a game.
We weren't as impressed by the SD39P2's motherboard. As our last motherboard Labs test shows, Intel 975X-equipped motherboards tend to get beaten to a pulp by boards equipped with the cheaper P965 chipset, since it sports the newer, faster ICH8R Southbridge and is a better overclocker. Frankly, the P965 is the obvious choice for any system built for Intel's Core 2 processors, so it's puzzling that Shuttle has revised the SD37P2, but stuck with the pricier yet inferior 975X chipset. As we saw with Shuttle's XPC SD37P2, the 975X can prove to be the undoing of any system when it comes to speed.
In terms of I/O ports, the SD39P2 is resolutely modern. You won't find any PS/2 ports, so you may have to buy a USB mouse and keyboard. Thankfully, though, there are six USB 2 ports on the back of the Shuttle, and a further two on the front, so it's unlikely that you'll run out of free sockets. You'll also find the usual 8-channel analogue audio outputs, in addition to both digital coaxial and optical S/PDIF ports. There's even a handy external CMOS reset button, so you can quickly return to the default settings if an overclock goes awry.
Performance
The motherboard inside the SD39P2 might be small, but this doesn't mean that it should be any slower than a full-sized ATX board. Unlike the AOpen, the SD39P2 is large enough to cope with our usual test graphics card, a dual-slot GeForce 7900 GTX, which we matched with the 2.66GHz Core 2 Duo E6700, a 250GB Samsung SpinPoint S-ATA II hard disk and 2GB of Corsair RAM.
The SD39P2's benchmark scores are similar to those of 975X-based motherboards, such as the Asus P5W DH Deluxe. The SD39P2 matched the Asus' score of 1.80 in the Paint Shop Pro test, and when it came to DVD encoding, it scored 1.62 to the 1.63 of the Asus. Compared with a motherboard such as the P965-based Asus P5B Deluxe WiFi-AP, however, the Shuttle lagged slightly - the P5B scored 1.83 in the Paint Shop Pro test and 1.64 in DVD encoding. The differences aren't huge but, considering that better silicon is out there, it seems silly to stick with the 975X.
When it came to overclocking, however, the limitations of the 975X chipset, combined with the heat generated by components being contained in a small space, emerged to haunt the SD39P2. Things started off well and, without any increase in CPU voltage, we managed to increase the speed of our 2.66GHz CPU to 3GHz, using a 300MHz FSB. Slightly increasing the voltage and trying to reach headier heights sent the SD39P2 into a hot-headed huff. The CPU refused to run at full speed, although touching the scorching Northbridge heatsink inside the case made us realise that if we were that hot, we'd probably refuse to work too.
Conclusion
The SD39P2 has most of the drawbacks of the SD37P2, which isn't surprising, considering that the only difference between the two machines is the SD39P2's single 16x PCI-E slot as opposed to the two slots on the SD37P2. The P2 chassis is good-looking and quiet, but becomes very hot - we suspect that some form of active cooling on the Northbridge, or near the motherboard VRMs, would have helped our overclocking endeavours.
Still, some compromises are to be expected if you opt for a small form factor. If you don't mind being limited to a modest overclock, the Shuttle XPC SD39P2 offers enough free space and power to house a very respectable portable gaming rig - it's just a shame that it doesn't use the P965 chipset, as it could be even better.
