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Shuttle's XPC SN25P mini-barebones system

At long last?

Manufacturer Shuttle
Model XPC SN25P
Price (MSRP) $420
Availability Soon

WITH EXPANSIVE INTERNALS that can accommodate up to three hard drives, a trio of temperature-controlled cooling zones, tool-free drive rails, and a robust 350W power supply, the P series is undoubtedly the pinnacle of Shuttle's XPC chassis line. Enthusiasts have been eagerly awaiting a P-series XPC for the Athlon 64, but in the seven months since the chassis' introduction, the P series has been a Pentium 4-only affair. That all changes today with the arrival of Shuttle's XPC SN25P.

Sporting a 939-pin socket for the Athlon 64, an nForce4 chipset, PCI Express, and an integrated Envy24PT audio controller, the XPC SN25P could be the best small form factor barebones system to date. Does it deliver on its considerable potential? Was it worth the wait? Read on to find out.

The specs
We'll kick things off with a look at the SN25P's spec sheet. Right off the bat, notice that the system is based on NVIDIA's vanilla nForce4 core logic chip, not the Ultra or SLI versions.

CPU support Socket 939-based Athlon 64 processors
Chipset NVIDIA nForce4
Interconnect NA
Expansion slots 1 PCI Express x16
1 PCI Express x1
Memory 2 184-pin DIMM sockets
Maximum of 2GB of DDR266/333/400 SDRAM
Storage I/O Floppy disk
1 channels ATA/133 with RAID 0, 1, 0+1 support
4 channels Serial ATA II with RAID 0, 1, 0+1 support
Audio 8-channel audio via VIA Envy24PT PCI audio controller, VIA VT1617A codec, and Wolfson WM8728 DAC
Ports 1 PS/2 keyboard
1 PS/2 mouse
1 serial
USB 2.0 (rear)
2 USB 2.0 (front)
1 Firewire via VIA VT6307 (rear)
1 Firewire (front)
1 RJ45 10/100/1000 Gigabit Ethernet

1 analog front out
1 analog bass/center out
1 analog surround out
1 analog rear out
1 analog line in
1 analog mic in (front)
1 analog headphone out (front)
2 digital S/PDIF outputs (RCA and TOS-Link)
1 digital S/PDIF input (TOS-Link)
BIOS Phoenix AwardBIOS
Bus speeds CPU: 200-250MHz in 1MHz increments
DRAM: 100, 133, 166, 200MHz
Bus dividers HT: auto, 1x, 2x, 3x, 4x, 5x
Voltages CPU: auto, 0.8-1.7V in 0.05V increments
DDR: auto, 2.7-2.9V in 0.1V increments
Chipset: auto, 1.6-1.7V in 0.05V increments
Monitoring Voltage, fan status, and temperature monitoring
Fan speed control CPU, system

What differentiates the nForce4 from its Ultra cousin? Surprisingly little. When employed in Socket 754 motherboards, the vanilla nForce4's HyperTransport link is supposed to be limited to 800MHz. That's not an issue for the Socket 939 SN25P, though. The system's nForce4 HyperTransport link runs at 1GHz, just like the Ultra's.

On the storage front, the vanilla nForce4 lacks the Ultra's support for 300MB/sec Serial ATA II transfer rates, but that's hardly worth shedding a tear over. Serial ATA II drives aren't available yet, and while short burst transfers may be able to take advantage of some of the extra bandwidth, even today's fastest 15K-RPM SCSI hard drives can't sustain transfer rates that would saturate Serial ATA's 150MB/s pipe. Apart from the lack of 300MB/s transfer rates, the nForce4's storage and RAID capabilities are identical to the Ultra's, so you're not missing much.

The only other feature that the nForce4 lacks is ActiveArmor acceleration for the chipset's integrated Gigabit Ethernet controller and firewall. The GigE controller and firewall are still there, just not the hardware acceleration, which could result in higher CPU utilization during network transfers.

The nForce4 doesn't differ from its Ultra brethren at all when it comes to integrated audio. Both offer generic AC'97 audio without hardware acceleration or support for high definition resolutions and sampling rates. Fortunately, Shuttle completely bypasses the nForce4's integrated AC'97 sound in favor of VIA's Envy24PT audio controller. The Envy24PT doesn't have hardware acceleration, but it does support higher sampling rates and resolutions. Considering the SN25P's lack of a PCI slot and the scarcity of PCI Express sound cards, it's nice to see Shuttle making an effort to compensate for the nForce4's anemic integrated audio.