Shuttle’s XPC ST20G5 mini-barebones system

Manufacturer Shuttle
Model XPC ST20G5
Price (MSRP) $350
Availability Soon
ALTHOUGH ATHLON 64 processors undoubtedly deliver an attractive price/performance ratio, the platform’s lack of a competent integrated graphics chipset makes it less appealing for budget and business systems. That changed with the introduction of ATI’s Radeon Xpress 200 chipset, which boasts a DirectX 9 integrated graphics processor (IGP) derived from the company’s successful R300 architecture. The Radeon Xpress 200 IGP’s R300 roots and Catalyst drivers not only ensure broad compatibility with existing games, they also come with an array of video deblocking and playback acceleration features, as well as solid multimonitor capabilities.

Despite its attractive feature set, motherboard manufacturers have been slow to release retail products based on the Radeon Xpress 200 chipset. Shuttle hasn’t shied away, though. The small form factor originator has a history of aggressively implementing new core logic chipsets, and they’ve come up with a cube based on the Radeon Xpress 200. With DirectX 9-class integrated graphics, dual monitor outputs, PCI Express, High Definition Audio, and a striking brushed aluminum chassis, the ST20G5 promises to be the most well-rounded XPC for Athlon 64 processors. Read on to see if the system lives up to its potential.

The specs
As usual, we’ll kick things off with a look at the ST20G5’s spec sheet. We’ll only be covering the highlights here; for a more in-depth look at the Radeon Xpress 200, see our review of the chipset.

CPU support Socket 939-based Athlon 64 processors
Chipset ATI Radeon Xpress 200
North bridge ATI RS480
South bridge Uli M1573
Interconnect 1GB/sec (2 lanes PCI Express)
Expansion slots 1 PCI Express x16
1 32-bit/33MHz
Memory 2 184-pin DIMM sockets
Maximum of 2GB of DDR266/333/400 SDRAM
Storage I/O Floppy disk
1 channels ATA/133
2 channels Serial ATA with RAID 0, 1 support
Audio 8-channel audio via Uli M1573 south bridge and Realtek ALC880 codec
Ports 1 PS/2 keyboard
1 PS/2 mouse
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 via Broadcom 5751

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)
1 digital S/PDIF output (TOS-Link)
1 digital S/PDIF input (TOS-Link)

BIOS Phoenix AwardBIOS
Bus speeds HT: 200-232MHz in 1MHz increments
DRAM: 100, 133, 166, 200MHz
LDT: 1000, 800, 600, 400, 200MHz
Voltages CPU: auto, 0.8-1.7V in 0.05V increments
DDR: auto, 2.7-2.9V in 0.1V increments
Chipset: auto, 1.85-1.95V in 0.05V increments
Monitoring Voltage, fan status, and temperature monitoring
Fan speed control CPU/System

The ST20G5 is built around a core logic combo of ATI’s RS480 north bridge and ULi’s M1573 south bridge. It’s rare to see north and south bridge chips from different companies working together like this, but ULi designed the M1573 to complement ATI’s latest north bridge chips. It also helps that the RS480 is designed to interface with a south bridge chip over a pair of PCI Express lanes rather than over a proprietary interconnect.

With the Athlon 64’s memory controller sitting on the CPU die, the RS480’s biggest features are its PCI Express interface and integrated graphics processor (IGP). Looking at PCI Express, the RS480 serves up 20 lanes of connectivity in addition to the two lanes it uses for a north/south bridge interconnect. The ST20G5’s PCI-E x16 slot consumes 16 of those lanes, with an additional lane used by the system’s Broadcom 5751 Gigabit Ethernet controller. That’s it for PCI Express; although the chipset has PCI-E lanes to spare, Shuttle has opted to equip the cube with a standard 32-bit, 33MHz PCI slot instead of a PCI-E x1.

The RS480’s biggest claim to fame is its integrated graphics processor, which is based on the same RS300 core architecture that ATI has been riding since the Radeon 9700. R300 heritage gives the RS480 IGP full DirectX 9 support, although the chip only has two pixel pipelines running at 350MHz. Even so, the Radeon Xpress 200 IGP has already proven superior to Intel’s GMA 900 IGP. The Radeon Xpress 200 doesn’t really have any DirectX 9-class competition on the AMD side of the fence, either.

Some Radeon Xpress 200 graphics configurations add a bit of RAM on the motherboard to boost performance. The ST20G5 doesn’t have any “SidePort” RAM chips onboard, so the IGP will have to use only shared system memory for its frame buffer.

As far as features go, the Radeon Xpress 200 north bridge is reasonably current. The same can be said for the ST20G5’s ULi 1573 south bridge, which supports Intel’s “Azalia” High Definition Audio standard and Serial ATA RAID with Native Command Queuing. While RAID and NCQ are nothing new, the ULi 1573 is the first south bridge chip to bring 32-bit/192kHz audio to the Athlon 64.

Outside the box
The ST20G5 is built using the same G5 chassis that Shuttle has previously used in the SN95G5 and SB77G5. Since we’re already quite familiar with the G-Series chassis, I’ll confine much of my commentary to features that differentiate the ST20G5 from the rest of the G5 series.

Brushed aluminum dominates the ST20G5’s finish, right down to its gorgeous faceplate.

The aluminum finish is striking, classy, and definitely appeals to more industrial tastes. It almost looks a little too good, at least when compared with the system’s plastic components. The plastic’s gray color and smooth finish aren’t a perfect match for the brushed aluminum, and it ends up looking comparatively cheap.

Don’t get me wrong; I think the ST20G5 looks great. The plastic bits just come across as a little cheesy next to the swanky brushed aluminum.

Drive bay doors hide the ST20G5’s external 3.5″ and 5.25″ drive bays, and its front port cluster.

Shuttle boldly embosses its name across the side of the system, right above rows of ventilation holes the perforate both sides of the case’s aluminum skin.

A wide-open grill provides plenty of ventilation at the ST20G5’s rear, which is largely similar to other G5 cubes. The Radeon Xpress 200 IGP’s ability to power both VGA and DVI monitor outputs is unique to the ST20G5, though. Unfortunately, we found our system’s VGA signal quality to be a little lacking. While the Windows desktop was crisp and clear up to 1024×768 at 75Hz, the display had a slight but noticeable wobble at higher resolutions and refresh rates. DVI output was flawless up to 1280×1024, which is as high as my LCD monitors go. We couldn’t get the DVI output to work with any of the DVI-to-VGA adapters in our labs, though. It’s possible that the Radeon Xpress 200 is only capable of powering a single analog monitor.

Despite its limitations, the ST20G5’s VGA and DVI dual monitor output is unique in the small form factor world. However, it’s a little curious that a composite or S-Video output isn’t included. That somewhat limits the system’s suitability for home theater PCs, although one could always add a discrete graphics card with more video output options.

Opening ‘er up
The G-chassis’ internals aren’t as slick or tool-free as Shuttle’s P-Series cubes, but they get the job done.

Both the drive tray and cooling system pop out, which definitely helps with system assembly.

The cube’s PCI Express x16 slot sits on the left edge of the motherboard, making it impossible to use double-wide graphics cards without hacking up the case’s aluminum shell.

Memory slots are located on the right side of the system along with the floppy port. Normally, the floppy port wouldn’t be worth mentioning, but you’ll actually need it to install Windows, because the OS isn’t bundled with Serial ATA drivers for the ULi M1573 south bridge. Unfortunately, the only way the Windows XP installation routine can load third-party storage drivers is from a floppy drive.

The ST20G5’s motherboard layout is typical of a G-Series system, although it’s sporting a couple more coolers than we’re used to seeing.

In addition to an active north bridge cooler, the motherboard also features passive south bridge and VRM heat sinks. Since tiny chipset fans generally tend to develop and annoying whine over time, we’re not big proponents of active chipset cooling. However, given the ST20G5’s form factor limits, there may not be enough room for a passive heat sink large enough to keep the north bridge chip cool.

Cooling, power, and SurroundView
Speaking of cooling, Shuttle’s venerable ICE cooler also makes an appearance in the ST20G5.

The heat pipe design draws heat away from the CD to a series of radiator fins at the rear of the system. These fins are cooled by a temperature-controlled 92mm exhaust fan, which is thoughtfully mounted on rubber washers to dampen vibrations. The fan even has a four-pin BTX-style header that allows for linear speed control.

Like other G5 cubes, the ST20G5 is powered by a 240W PSU that should provide enough juice for the limited amount of hardware one can actually cram into the system.

Those who add an ATI graphics card to the ST20G5 will also be treated to SurroundView, which can combine the video outputs of the graphics card and IGP to power up to four monitors at once. Four-monitor output might be a little excessive for most users, but SurroundView can also be leveraged to drive a pair of DVI-equipped LCDs without resorting to analog output. Just keep in mind that the ST20G5’s DVI output can’t power an analog display, even with a plug adapter.

Although the ST20G5’s chipset-based graphics core may lend itself primarily to consumer and business applications, the system’s BIOS should keep most enthusiasts happy.

Those who will be using the IGP can set its frame buffer as large as 128MB and choose between a 300 or 350MHz core clock speed. Running the graphics chip at a slower speed shouldn’t hurt its performance in 2D applications and may allow the cube to run slightly cooler. Thanks to temperature-controlled fans, slightly cooler should also mean slightly quieter.

The BIOS also comes with a decent array of memory timing controls, including an optional 1T command rate. We’ve seen several Athlon 64 motherboards provide more extensive memory timing options, but there’s enough here for most enthusiasts.

Shuttle also includes lower HyperTransport multipliers that will help keep the processor link running stable during overclocking.

Unfortunately, HT link speeds are only available up to 232MHz. CPU multiplier control is also confined to 1x rather than 0.5x steps, limiting one’s ability to fine-tune the processor clock speed. At least the PCI and PCI Express clocks appear to be locked at stock speeds, although the BIOS doesn’t offer explicit control over either.

On the voltage front, CPU voltages are available as high as 1.7V. That’s probably as high as you’d want to go in a small form factor system with such limited cooling.

For most users, noise control may be more important than overclocking or tweaking options, so it’s a good thing the ST20G5 offers plenty of fan speed control. The BIOS offers four Noise Control settings that run the system fan at a constant speed until the processor hits 80C, at which point the fan cranks up to full throttle. Users can also select a Smart Fan or one of several Temp Control settings, which linearly ramp fan speeds to keep the processor at a pre-defined temperature.

Although there are plenty of fan speed options in the BIOS, it would be nice if Shuttle also gave users control over the Smart Fan’s temperature trigger. Since the entire system depends on a single cooling fan, temperature- or fan failure-based shutdown and alarm conditions would also be useful additions.

Our testing methods
Today we’ll be comparing the ST20G5’s performance to that of Abit’s Fatal1ty AN8, Gigabyte’s GA-K8VT890-9, Soltek’s SL-K890PRO-939, Foxconn’s NF4UK8AA, DFI’s LANParty NF4 Ultra-D, and Shuttle’s XPC SN25P. The ST20G5’s application performance was tested with the same GeForce 6600 GT as our other test systems, and also with the Radeon Xpress 200’s IGP, which was configured with a 128MB frame buffer. Peripheral performance was tested with the GeForce 6600 GT installed.

All tests were run three times, and their results were averaged, using the following test systems.

Processor Athlon 64 3500+ 2.2GHz
System bus HT 16-bit/1GHz downstream
HT 16-bit/1GHz upstream
Motherboard Shuttle XPC ST20G5 Shuttle XPC SN25P Abit Fatal1ty AN8 Foxconn NF4UK8AA DFI LANParty NF4 Ultra-D Soltek SL-K890PRO-939 Gigabyte GA-K8VT890-9
BIOS revision FT20S905 FN25S01A Version 12 1.1 NF4LD209 T1 F1
North bridge ATI RS480 NVIDIA nForce4 NVIDIA nForce4 Ultra VIA K8T890
South bridge ULi M1573 VIA VT8237
Chipset drivers ATI CATALYST 5.3
ForceWare 6.39 Chipset: Hyperion 4.55
SATA: 4.10a
Memory size 1GB (2 DIMMs)
Memory type OCZ PC3200 EL Platinum Rev 2 DDR SDRAM at 400MHz
CAS latency (CL) 2
RAS to CAS delay (tRCD) 2
RAS precharge (tRP) 2
Cycle time (tRAS) 5
Hard drives Western Digital Raptor WD360GD 37GB SATA
Maxtor DiamondMax Plus D740X 40GB ATA/133
Audio Uli M1573/ALC880 Envy24PT nForce4/ALC658 nForce4/ALC850 VT8237/ALC850
Graphics NVIDIA GeForce 6600 GT with ForceWare 66.93 drivers
OS Microsoft Windows XP Professional
OS updates Service Pack 2, DirectX 9.0c

Thanks to OCZ for providing us with memory for our testing. If you’re looking to tweak out your system to the max and maybe overclock it a little, OCZ’s RAM is definitely worth considering.

With the exception of the XPC SN25P, our test systems were powered by OCZ PowerStream power supply units. The PowerStream was one of our Editor’s Choice winners in our latest PSU round-up.

We used the following versions of our test applications:

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at a 75Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests. Most of the 3D gaming tests used the Medium detail image quality settings, with the exception that the resolution was set to 640×480 in 32-bit color.

All the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

Memory performance

Using the ST20G5’s integrated graphics slows the system’s performance in our memory bandwidth and latency tests, but the cube is largely competitive with a discrete graphics card installed.


In WorldBench, the ST20G5 fares particularly well with a 6600 GT installed. The system’s integrated graphics performance is perhaps even more impressive, though. Despite a poor showing in WorldBench’s 3D Studio Max rendering tests, the ST20G5 IGP is competitive throughout the rest of the suite.


The IGP obviously can’t keep up in our gaming tests, especially not against a GeForce 6600 GT. Still, 35 frames per second in Unreal Tournament and nearly 50 frames per second in Far Cry are quite respectable for an integrated graphics controller.

Cinebench rendering

The ST20G5 generally stays with the pack in Cinebench, although the IGP stumbles in both OpenGL shading tests.

Sphinx speech recognition

The IGP also slows the ST20G5’s performance in Sphinx, but the system performs better with a discrete graphics card installed.

Audio performance

The ST20G’s 3D audio CPU utilization is among the lowest we’ve seen from recent Athlon 64 platforms. It’s still software audio, though; those few audio solutions with hardware acceleration consume fewer CPU cycles.

Audio quality
I used an M-Audio Revolution 7.1 card for recording in RightMark’s audio quality tests. Analog output ports were used on all systems. To keep things simple, I’ve translated RightMark’s word-based quality scale to numbers. Higher scores reflect better audio quality, and the scale tops out at 6, which corresponds to an “Excellent” rating in RightMark.

According to RightMark Audio Analyzer, the ST20G5’s audio quality is at least as good—if not better—than the other Athlon 64 platforms we tested. My ears confirm those results. The ST20G5 sounds pretty good, at least for integrated audio.

ATA performance
ATA performance was tested with a Maxtor 740X-6L ATA/133 hard drive using HD Tach 3.01’s 8MB zone setting.

The ST20G5’s ULi 1573 IDE controller has no problem keeping up with the competition in HD Tach.

Serial ATA performance
Moving to Serial ATA, we tested performance with a Western Digital Raptor WD360GD SATA hard drive. Again, we used HD Tach 3.01’s 8MB zone test.

Although its burst speed is a little lower than some of the other Athlon 64 platforms we tested, the ST20G5’s Serial ATA performance is generally good.

USB performance
Our USB transfer speed tests were conducted with a USB 2.0/Firewire external hard drive enclosure connected to a 7200RPM Maxtor 740X-6L hard drive. Our enclosure is neither the fastest USB 2.0 nor Firewire platform, but it should help us spot any egregious problems with a motherboard’s implementation of either feature. We tested with HD Tach 3.01’s 8MB zone setting.

The ST20G5 definitely has some performance problems with USB. In addition to slower transfer rates, CPU utilization is also quite high.

Firewire performance
Our Firewire transfer speed tests were conducted with the same external enclosure and hard drive as our USB transfer speed tests.

Shuttle finds some redemption in our Firewire tests, but the ST20G5’s transfer rates are still slower than most of the other platforms we tested.

Ethernet performance
We evaluated Ethernet performance using the NTttcp tool from Microsoft’s Windows DDK. The docs say this program “provides the customer with a multi-threaded, asynchronous performance benchmark for measuring achievable data transfer rate”.

We used the following command line options on the server machine:

ntttcps -m 4,0, -a

..and the same basic thing on each of our test systems acting as clients:

ntttcpr -m 4,0, -a

Our server was a Windows XP Pro system based on Chaintech’s Zenith 9CJS motherboard with a Pentium 4 2.4GHz (800MHz front-side bus, Hyper-Threading enabled) and CSA-attached Gigabit Ethernet. A crossover CAT6 cable was used to connect the server to each system. The nForce4 boards were tested with the NVIDIA Firewall and Jumbo Frames disabled.

Despite the fact that it uses a PCI Express GigE controller, the ST20G5’s Ethernet throughput is quite low. It’s hard to determine if the bottleneck is the Broadcom GigE chip or the RS480 north bridge’s PCI Express interface, but it’s disappointing either way. Update 6/13/2005 — We recently discovered that the ntttcp CPU utilization results included in this review were incorrect. The CPU utilization results have been removed, but they didn’t factor prominently into our overall conclusion, so that remains unchanged. A full explanation can be found here.

For our overclocking tests, we swapped our low-latency OCZ PC3200 memory out of the ST20G5 in favor of some of the OCZ’s PC4400 sticks, which are rated for higher clock speeds at more relaxed latencies. PC4400 memory is designed to operate at speeds of up to 550MHz, so it shouldn’t bottleneck our overclocking efforts. However, running the PC4400 memory at more relaxed 2.5-3-3-8 timings could result in lower overall performance if we can’t crank the clock speed high enough to compensate.

In testing, we were able to get the ST20G5 stable with HT link speeds as high as 232MHz. Unfortunately, the BIOS doesn’t provide higher HT link speed options.

Our HT overclock improves performance in Sphinx and Unreal Tournament 2004, but keep in mind that the CPU is also running at 2.32GHz—120MHz higher than its stock clock speed.

Noise levels
We measured noise levels 1″ from the ST20G5’s front, side, and rear using an Extech Model 407727 Digital Sound Level Meter. Measurements were taken after 10 minutes at idle, and then after another 10 minutes of a [email protected] CPU load. We also measured the noise levels of Shuttle’s XPC models SN25P, SB95P V2, and SB86i for comparison. The SN25P was equipped with identical hardware to the ST20G5, while SB95P V2 and SB86i were equipped with a Pentium 4 520 2.8GHz processor and Radeon X600 XT graphics card. The ST20G5, SN25P, and SB95P V2 used their default Smart Fan setting, but the SB86i requires its Mid fan speed setting to maintain stability under load.

With graphics handled by the IGP, the ST20G5’s noise levels are impressively low. However, the SN25P’s noise levels are lower when a graphics card is installed.

With an expected MSRP of $350, the ST20G5 looks like a pretty sweet deal. $350 is relatively inexpensive for an XPC with this many features, and you won’t find another Athlon 64 cube with DirectX 9-class integrated graphics, a DVI output, and SurroundView, not to mention support for Native Command Queuing and High Definition Audio. You’d be hard-pressed to find a small form factor system with as nice a finish as the ST20G5’s brushed aluminum, too.

Unfortunately, the box isn’t perfect. The ST20G5’s USB and Gigabit Ethernet performance are disappointing, and our sample’s VGA signal quality had some issues above 1024×768 at 75Hz. The BIOS also needs a little work, most notably support for higher HT link speeds and 0.5x CPU multipliers for overclocking. Those are all just quibbles, but their combined impact is enough to tarnish the system’s otherwise perfect finish.

At the end of the day, the ST20G5’s real appeal is its integrated graphics, which is a cut above competing solutions. Enthusiasts who have no intention of using the IGP, either as a primary graphics solution or for SurroundView, may have a hard time swallowing the ST20G5’s drawbacks. For enthusiasts planning to run a discrete graphics card, Shuttle’s nForce4-powered SN25P is a more appealing XPC.

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