BIOS options
If you really want to overclock the SP35P2, you'll need to drop into the BIOS. Fortunately, Shuttle has provided all sorts of options to play with, including full control over DDR2 memory timings alongside a host of bus speed, multiplier, and voltage options.

Bus speeds FSB: 333-600MHz in 1MHz increments
PCIe: 100-200MHz in 1MHz increments
DRAM: 667, 800, 1067MHz
Bus multipliers CPU: 6x-8x (Core 2 Duo E6750)
Voltages CPU: +0.01-0.5V in 0.01V increments
DRAM: 1.8-2.5V in 0.025V increments
FSB: 1.25-1.35V in 0.05V increments
NB: 1.3-1.4V in 0.05V increments
SB(1.5): 1.55-1.65V in 0.05V increments
 SB(1.05): 1.10-1.20V in 0.05V increments
Monitoring Voltage, fan status, and temperature monitoring
Fan speed control CPU, chassis

The P35 Express chipset technically only supports front-side bus speeds up to 333MHz, but if you want to run a QX9770, you can push the FSB to 400MHz in the BIOS. And it's stable, too, but more on overclocking a little later. One thing that may hinder bus speed tweaking is the BIOS's relatively short list of memory speed options. We'd prefer to see more variety here, ideally explicit control over a broader range of memory bus dividers.

Things look pretty good on the voltage front. Although processor overvolting is limited to half a volt, you wouldn't want to pump more juice into a chip running in such a small enclosure. Memory voltage options up to 2.5V should cover most of the swanky DIMM spectrum, as well, equipping the XPC for all but the most extreme overclocking endeavors.


Additional fan speed control options are also available in the BIOS, although these are a little more limited than what's provided through XPC tools. Notably missing is control over threshold temperatures and ramping ratios. Both would be nice to have, particularly for those running alternative operating systems that won't have access to XPC Tools, which is Windows-only.

Specifics on specifications
An XPC review wouldn't be complete without a quick look at the system's spec sheet.

CPU support LGA775-based Celeron, Pentium 4/D, Core 2 processors
North bridge Intel P35 Express
South bridge Intel ICH9R
Interconnect DMI (2GB/s)
Expansion slots 1 PCI Express x16
1 32-bit/33MHz PCI
Memory 4 240-pin DIMM sockets
Maximum of 8GB of DDR2-667/800/1066 SDRAM
Storage I/O Floppy disk
1 channel ATA/100
4 channels 300MB/s Serial ATA with RAID 0, 1, 10, 5 support
Audio 8-channel HD audio via ICH9R and Realtek ALC888 codec
Ports 8 USB 2.0 with headers for 2 more
 1 RJ45 10/100/1000 via Marvell 88E8056
2 1394a Firewire via Texas Instruments TSB43AB22A
2 eSATA

 1 analog front out
 1 analog bass/center out
 1 analog rear out
1 analog surround out
1 analog headphone out
1 analog mic in
1 analog line in
1 digital coaxial S/PDIF output
1 digital TOS-Link S/PDIF output
1 digital TOS-Link S/PDIF input

We've covered most of the interesting bits already, but there are a couple of stragglers worth pointing out. First, note that the SP35P2's Marvell 88E8056 Gigabit Ethernet chip uses a PCI Express interface, so it won't be forced to share limited PCI bus bandwidth with other devices—not that the XPC's single PCI slot leaves much room for conflict on that bus. The system's Texas Instruments Firewire chip is PCI-based, though. That about rounds up all the scandalous details we can pry from the spec sheet, so it's on to benchmarks.