Diving inside
Digging deeper into the XPC chassis is easy; unscrew four thumbscrews, and the enclosure's outer skin slides off to reveal its internals.
From above, the first thing we see is a pair of 3.5" drive bays primed for Serial ATA hard drives. Shuttle does all the cable routing for you, ensuring the SATA power and data cables are exactly where you need them. However, we should note that due to how the cages are designed, only SATA drives are supported. In fact, you have to use the SATA power connector rather than the alternative four-pin molex power connector that's available on some drives.
Screws hold the drive bays in place, which is a bit of a step back for Shuttle. The original P-series chassis used tool-free drive bays that snapped in place using plastic clips. Screws aren't really a hassle, but it's always nice to work on a system without having to bust out any tools.
Once we remove the hard drive bays, the XPC's lower drive cage can be extracted. This houses the external 3.5" and 5.25" drive bays. The former is perfect for a zillion-in-one card reader or, if you're feeling really nostalgic, a floppy drive.
Around the right-hand side of the system we catch our first glimpse of a new array of heatpipes and passive cooling elements that cover the XPC's chipset and voltage regulation circuitry. Not even Shuttle is immune to the heatpipe trend that has gripped enthusiast motherboards, and given the XPC's cramped internals, a little additional cooling certainly can't hurt.
From this side we also have access to the system's PCI and PCI Express x16 slots. The x16 slot is on the outside, so if you're willing to sacrifice PCI connectivity, you can squeeze in a double-wide graphics card. Even the beefy GeForce 7900 GTX will fit, although it's a tight squeeze.
The problem isn't the location of the slot, but the mass of cabling that extends up from the motherboard to the power supply and rest of the chassis. I had to fiddle with the wires to flatten them out a little before a double-wide graphics card would fit inside the chassis, and even then there was plenty of direct contact between the wires and the graphics card's cooler shroud. You'll want to be careful to ensure that there are no errant wires that could get caught in your graphics card's cooling fan.
Speaking of being careful, watch the motherboard when installing graphics cards. Larger cards are a tight squeeze, and you don't want the PCI back plate to dig into the surface of the motherboard as you slide it into place. Shuttle put a piece of plastic next to the PCIe x16 slot to protect the motherboard in older XPC systems, but that protective plastic is nowhere to be found on the SP35P2.
Spinning XPC to the left we find a quartet of DIMM slots. Memory expansion capacity hasn't been compromised here, with the system supporting up to 8GB of DDR2 memory. There's even enough clearance for Corsair's taller Dominator memory modules.
Just above the DIMM slots is the SP35P2's power supply. This unit is rated for up to 120W across its 3V and 5V rails, up to 360W across its dual 12V lines, and 400W of maximum power output. One six-pin PCI Express connector is included for power-hungry graphics cards, as well.
To get at the CPU socket, we have to remove the XPC's ICE cooler and swing wide a plastic mount that holds an 80mm intake fan in place. Processor installation is still a little tight, but that can't be avoided in an enclosure this small. In fact, of all the small form factor chassis we've worked with, the P-series is easily the friendliest when it comes to poking around.
