Shuttle’s XPC SN21G5 barebones system

Fortunately, Shuttle hasn’t completely forgotten about do-it-yourself PC builders. In fact, the company has just launched a new addition to its small form factor barebones lineup. The XPC SN21G5 packs NVIDIA’s GeForce 6100 integrated graphics chipset, a carefully massaged ICE cooler, and room for a GeForce 7800 GTX into Shuttle’s proven G5 chassis.

Can the diminutive SN21G5 keep up with the latest full-sized ATX motherboards? Perhaps more importantly, how does it compare with Shuttle’s last cube with integrated graphics for the Athlon 64? Keep reading to find out.

The specs
As usual, we’ll kick things off with a run down the SN21G5’s spec sheet. Things might look a little bare, but remember, Shuttle squeezes it all into a form factor that’s roughly the size of a toaster.

NVIDIA’s GeForce 6100 integrated graphics chipset anchors the SN21G5, giving the system DirectX 9-class graphics right out of the box. Don’t expect the IGP to keep up with today’s latest and greatest graphics cards, though. The GeForce 6100 has only two pixel pipelines and one vertex shader. With a 425MHz core clock speed, that doesn’t make for particularly inspiring fill rates or shader crunching power. The chip’s GeForce 6-series heritage should at least ensure compatibility with a wide range of games, even if they can only be run at lower resolutions and detail levels.

The GeForce 6100 is actually the lesser of NVIDIA’s two integrated graphics processors, and it’s missing a number of features available on the pricier GeForce 6150 IGP. Among them are an integrated TV encoder, TMDS transmitter for DVI output, support for high definition MPEG2 and WMV playback, and high-quality video scaling. Those features seem particularly appropriate for small form factor systems that are often deployed in living rooms as media-centric PCs, making Shuttle’s use of the GeForce 6100 a little puzzling.

In addition to its integrated graphics processor, the GeForce 6100 north bridge comes equipped with 17 PCI Express lanes. 16 of those lanes feed the SN21G5’s x16 slot, which should allow users to easily bypass the cube’s integrated graphics. However, the SN21G5 lacks PCI Express x1 slots and peripherals, so the extra lane goes unused. Given the lack of PCI Express peripherals, particularly audio cards, we can’t complain about Shuttle’s decision to forgo a PCI Express x1 slot in favor of plain old PCI. However, the cube could use a PCI Express Gigabit Ethernet chip to bolster its networking spec.

NVIDIA usually integrates a Gigabit Ethernet controller right into its chipsets, but the SN21G5’s low-end nForce 410 MCP only supports 10/100 Fast Ethernet. Shuttle doesn’t include a PCI-based GigE controller, either, making the SN21G5 the first platform we’ve reviewed in a long, long time that’s stuck at 100Mbps.

As you might expect, the nForce 410’s 10/100 Ethernet controller doesn’t make use of NVIDIA’s ActiveArmor hardware acceleration engine. It does work with NVIDIA’s firewall software, though. The nForce 410 also supports up to two Serial ATA devices, complete with 300MB/s transfer rates and Native Command Queuing. RAID support is limited to RAID 0 or 1, but in a small form factor system that can only accommodate two hard drives, that’s hardly a concern.

Unfortunately, the SN21G5’s basic AC’97 audio codec is a bit of a concern. The nForce 410 actually supports both AC’97 and High Definition Audio, but Shuttle has inexplicably chosen to go with the inferior AC’97. High-definition codec chips do cost a little more; however, that’s money well-spent for a system with such limited upgrade capacity.

Thinking outside the box
As its name implies, the SN21G5 reprises Shuttle’s classic G5 chassis. The G-series chassis has been around for what seems like forever, and its G5 derivative is nearly a year and a half old. The chassis still looks great, though, even if it lacks many of the useful features found in Shuttle’s newer P-series platform.

Perhaps in a tribute to the late, great Johnny Cash, Shuttle dresses the SN21G5 in black. The brushed metal finish is particularly attractive, and it should keep fingerprints at bay. However, Shuttle isn’t able to maintain the brushed metal look throughout. A smattering of glossy black plastic breaks up the aesthetic and cheapens the look of the cube a little. Of course, if you’re not particularly fond of brushed metal, that might not be a bad thing.

Since ports and expansion bays don’t necessarily go with brushed black metal, either, Shuttle hides them behind a series of retractable doors. Separate doors hide the front port array—which includes mic and headphone jacks, a couple of USB ports, and a mini Firewire port—and the system’s external 3.5″ expansion bay. That expansion bay should come in handy for anyone who wants to add a media card reader to the system. Shuttle’s actually integrated media card readers into several of its XPCs, but sadly, none of the G5-based cubes.

In addition to hiding the front port cluster and 3.5″ expansion bay, the SN21G5 also stealths the system’s external 5.25″ expansion bay. This arrangement neatly prevents beige optical drives from clashing with the SN21G5’s classy black exterior, and Shuttle has even rigged a handy eject button extender that opens and closes drives with ease.

From the rear, we can see the rest of the SN21G5’s expansion ports. There’s no room for a parallel port, but Shuttle manages to squeeze in most of the essentials. You won’t find DVI or TV output ports, though. Neither is supported by the GeForce 6100 integrated graphics processor, and that definitely limits the SN21G5’s appeal as not only a business desktop but also as a home theater PC. Had Shuttle used the GeForce 6150 instead, the SN21G5 could have been equipped with DVI and a TV output that supports both standard and high definition displays.

While the SN21G5 lacks support for extra video outputs, Shuttle gets points for including a coaxial digital S/PDIF audio output. Not too many points, though. Most of Shuttle’s XPC systems have supported S/PDIF output and input, so the SN21G5 is actually a bit of a step down in that department.

Underneath the skin
Peeling back the SN21G5’s brushed aluminum skin reveals the G5’s somewhat cramped internals. However, thanks to years of gradual refinement, the tight G-series chassis is surprisingly easy to work on. Everything has its place, and cables are carefully routed to exactly where they’re needed.

The SN21G5’s internals look especially awkward from above, but with a removable drive bay cage and cooling assembly, it’s not nearly as bad as it looks. We’ll get to the drive cage and cooler in a moment, but first, note the position of the DIMM slots towards the bottom right-hand corner of the picture. Shuttle usually mounts the DIMM slots parallel to the PCI slot along the top edge of the board. This allows them to be easily accessed from one side of the chassis without having to remove anything other than the system’s skin. The SN21G5’s DIMM slots run perpendicular to that position, and their placement below the drive cage makes installing memory modules a little more complicated with some configurations. Longer graphics cards like the GeForce 7800 GTX obscure access to one set of DIMM slot retention tabs, necessitating the removal of the graphics card or drive cage just to swap out memory modules.

Removing a graphics card from the SN21G5 isn’t a big deal, as the x16 slot is located along the left edge of the system. That position does limit the SN21G5’s compatibility with wider graphics cards, though. You’ll have to take a dremel to the aluminum shell to accommodate double-wide designs like the GeForce 7800 GTX 512 and Radeon X1900 XT and XTX.

Around the right-hand side of the system, we have a good view of the SN21G5’s 250W power supply. The PSU is capable of pushing up to 16 amps over the 12V rail, and it had no problem handling a test system that included 2GB of memory, a 10K-RPM Raptor, a 130nm Athlon 64 FX-53 processor, and a GeForce 7800 GTX graphics card. Unfortunately, the power supply doesn’t have a six-pin PCI Express graphics card connector, so you’ll have to track down a four-pin Molex adapter to run the latest high-end graphics cards in the system.

While we have it in frame, it’s worth noting that the SN21G5’s PSU relies on only a pair of 40mm fans for cooling. We’ve used scores of Shuttle power supplies with similar cooling over the years, and with extended use, we’ve found that the fans tend to get a little loud. Most small-diameter fans suffer from increased noise levels over time, so the problem isn’t unique to the XPC. Our SN21G5 sample runs pretty quiet, but we’ve only had it for about a week.

The key to the G-series chassis’ ease of use is its drive cage, which can be popped out after removing just a couple of screws. Removing the cage opens up access to much of the SN21G5’s internals, including its 3.5″ and 5.25″ bays. Capacity is limited to one 5.25″ drive and two 3.5″ drives, but given the system’s cramped internals and limited air flow, I wouldn’t recommend running more than one hard drive anyway.

With just a little more work, it’s also possible to remove the SN21G5’s cooling assembly, which consists of a 92mm fan and an updated ICE heat sink. The fan uses a four-pin connector that allows for linear fan speed control, ensuring that fan speeds don’t repeatedly oscillate between high and low speed settings. Fan-induced vibrations are also dampened by a set of rubber washers that sit between the fan shroud and chassis.

When installed, the SN21G5’s cooling fan slides over a block of radiator fins at the rear of the system. Those fins are a part of the processor heat sink, which is connected to the CPU via a slender trio of heat pipes. Unlike previous ICE designs, the cooler actually screws directly into the chassis, through the motherboard. This retention design is incredibly sturdy, although unlike previous ICE retention clips, it does require a screwdriver.

With the exception of its retention mechanism, Shuttle hasn’t changed the ICE cooler much for the SN21G5. That’s probably a good thing, since it’s proven to be an effective design. The SN21G5 runs nice and quiet with an Athlon 64 FX-53 under the hood, although in our experience, Shuttle’s newer P-Series chassis is a little quieter.

At least some of the credit for the SN21G5’s low noise levels should go to the motherboard’s passive chipset cooling. Shuttle manages to keep the GeForce 6100 happy without a dedicated fan, something it couldn’t do with the Radeon Xpress 200-powered ST20G5. The GeForce 6100 is built using 90-nano fabrication technology, so that could be contributing to its relaxed cooling requirements.

Otherwise, the SN21G5’s motherboard doesn’t yield too many surprises. The floppy connector can be a bit of a pain to get at, but since few users actually need a floppy drive these days, it’s not that big of a deal. Shuttle can’t ditch the floppy port completely, though, as the Windows installation process still demands that third-party drivers for unrecognized storage controllers be loaded off a disk. Fortunately, Windows XP has no problem recognizing single drives connected to the nForce 410.

BIOS and tweaking software
Despite a smaller system stature, Shuttle’s XPC BIOSes have always been loaded with tweaking and overclocking options. The SN21G5’s BIOS is no exception.

Most of the SN21G5’s tweaking options are consolidated under Advanced Chipset Options. Here, you can play with the HyperTransport connections between the north and south bridge chips, and between the north bridge and processor. A couple of overclocking options also creep into the mix, with the BIOS allowing users to set the HT clock between 200 and 300MHz and the PCI Express clock between 100 and 145MHz.

The remainder of the SN21G5’s overclocking options are tucked away in the frequency and voltage control section of the BIOS. Here, you can manipulate the processor multiplier and the chipset, memory, and processor voltages. CPU voltages go all the way up to 1.7V, which is pretty impressive considering the fact that many full-size ATX boards top out at around 1.55V. Small form factor systems tend not to be particularly good overclockers due to their limited air flow, though.

To get at the SN21G5’s memory timings, we have to go back to the Advanced Chipset Options menu. All the important memory settings are there, although the BIOS doesn’t provide access to some of the more seldom-used timings available on other boards. The BIOS also doesn’t allow for an asynchronous memory clock faster than 200MHz, either.

Shuttle’s XPC systems had temperature-based fan speed control way before it was cool, and the SN21G5 doesn’t disappoint. Users can choose from nearly a dozen fan speed profiles, each of which offers a different balance of lower noise levels and better cooling performance. Shuttle offers even more control over fan speeds through its XPC Tools Windows software. However, Shuttle doesn’t currently have an XPC Tools config file that works with the SN21G5, so it’s impossible to run the app on the system.

Speaking of software that doesn’t work with the system, NVIDIA’s excellent nTune system utility doesn’t recognize the SN21G5 as an nForce platform. Shuttle’s working on the problem, and expects to support nTune in the future, but it’s not ready just yet.

Since the SN21G5 isn’t due to be available for a few weeks, it’s hard to get too worked up about missing XPC Tools and nTune support. However, it’s a little surprising that Shuttle is releasing yet another XPC system without BIOS-level alarm or shutdown conditions. The SN21G5 relies on a single fan to cool the processor and chassis, and if that fan fails, rising temperatures could damage system components. To protect against damage due to a catastrophic cooling failure, the SN21G5’s BIOS should at the very least include a fan failure or temperature-based system shutdown trigger.

Test notes
Today we’ll be comparing the SN21G5’s performance with that of a handful of enthusiast-oriented ATX boards, including DFI’s LANParty UT RDX200 CD-DR , ECS’s KA1 MVP Extreme, and Asus’s A8N32-SLI and A8R-MVP. We’ve also thrown in Shuttle’s last Socket 939 XPC system, Radeon Xpress 200-powered ST20G5, as it’s one of the SN21G5’s closest small form factor competitors.

Since the SN21G5 and ST20G5 both have video onboard, we’ve tested them with our GeForce 7800 GTX, and with their respective integrated graphics processors. The IGPs obviously aren’t going to be competitive with the 7800, but it should be interesting to see how the GeForce 6100 fares against the Radeon Xpress 200.

Before we move onto the benchmarks, it should be noted that we ran into a curious problem with the SN21G5 that prevented us from installing Windows XP on the system. For whatever reason, the XPC refused to load Windows XP’s installation routine off a CD. We tried a couple of different discs and different versions of Windows, to no avail. We’ve seen similar issues with other motherboards before, and they’ve been fixed by a BIOS update. Shuttle’s looking into the issue, but we don’t have a fix from them yet. Fortunately, we were able to copy an nForce-compatible Windows XP image over to the SN21G5 with no problems.

Our testing methods
All tests were run at least twice, and their results were averaged, using the following test systems.

Thanks to Corsair for providing us with memory for our testing. 2GB of RAM seems to be the new standard for most folks, and Corsair hooked us up with some of its 1GB DIMMs for testing.

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:

• SiSoft Sandra Standard 2005 SR3
• WorldBench 5.0
• TCD Labs HD Tach v3.01
• Futuremark 3DMark06 Build 1.02
• DOOM 3
• Far Cry v1.3
• Splinter Cell Chaos Theory v1.05
• RightMark Audio Analyzer 5.5
• RightMark 3D Sound 2.1
• NTttcp
• Cinebench 2003
• Sphinx 3.3

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at an 85Hz 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

Switching to integrated graphics lowers the SN21G5’s memory performance, but not by all that much. Otherwise, the SN21G5’s memory bandwidth and latency are comparable with our other Athlon 64 platforms.

WorldBench

With a GeForce 7800 GTX, the SN21G5 keeps pace with the fastest Athlon 64 platforms around. However, WorldBench’s OpenGL and DirectX rendering tests tax the GeForce 6100 enough to drop the SN21G5’s overall score by eight points. Still, the GeForce 6100 doesn’t fare as poorly in those tests as the Radeon Xpress 200.

Gaming

The SN21G5’s gaming performance is competitive when using a GeForce 7800 GTX, but frame rates are understandably much lower with the GeForce 6100. Interestingly, while the GeForce 6100 has no problem staying ahead of the Radeon Xpress 200 in DOOM 3, it’s slower in both Far Cry and Splinter Cell.

High quality gaming performance
Our first round of gaming tests were conducted with low in-game detail levels and display resolutions, but we’ve cranked things up for a second round. These tests use high resolutions, high detail levels, and anisotropic filtering and antialiasing, so they should be fairly indicative of how gamers play in the real world. We’ve tested each platform with a single GeForce 7800 GTX, and we’ve also benchmarked the Asus A8N32-SLI with a pair of 7800 GTXs running in SLI. We tested the KA1 MVP, RDX200, and A8R-MVP with single and dual Radeon X850 XT cards using ATI’s Catalyst 6.1 graphics drivers. For obvious reasons, we haven’t included integrated graphics results for either XPC.

The SN21G5 doesn’t support CrossFire or SLI, so it’s a little unfair to face it off against multi-GPU configurations. However, it’s worth checking out just how much of a performance jump the SN21G5 misses out on by not supporting dual graphics cards; after all, Shuttle does offer an XPC SN26P with SLI support. It’s also a good idea to confirm that the SN21G5 can keep up with other single-card configurations when we turn the eye candy up to 11.

It may not support multi-GPU graphics, but with a single GeForce 7800 GTX, the SN21G5 has no problem keeping up with the competition. Note that in 3DMark06, our nForce platforms score a little higher than those based on ATI’s Radeon Xpress 200 platform. NVIDIA has optimized its chipsets for GeForce graphics in the past, and it looks like they work a little better together in 3DMark06.

Cinebench rendering

The SN21G5 is competitive in Cinebench until the GeForce 6100 has to tackle the OpenGL shading tests. At least the NVIDIA IGP fares much better than the Radeon Xpress 200.

Sphinx speech recognition

Sphinx scores are pretty close with our GeForce 7800 GTX, and with their integrated graphics enabled, the SN21G5 and ST20G5 are evenly matched.

Audio performance

While the SN21G5 has marginally higher CPU utilization than our other platforms, none come close to the low CPU utilization achieved by hardware-accelerated 3D audio implementations. Note that neither the SN21G5 nor A8N32-SLI can complete the 32-buffer test. For whatever reason, Realtek’s AC’97 audio drivers top out at 25 buffers, while the company’s HD audio drivers go up to 32.

Audio quality
We 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.

The SN21G5 shadows the A8N32-SLI through our RightMark Audio Analyzer tests, which should come as no surprise considering that both use Realtek AC’97 codecs. Performance is consistent between the SN21G5’s front and rear audio outputs, but the SN21G5 still lags in the frequency response and total harmonic distortion tests. Anyone serious about audio quality will probably want to switch to the SN21G5’s coaxial digital output or install a PCI audio card with better DACs.

ATA performance
ATA performance was tested with a Seagate Barracuda 7200.7 ATA/133 hard drive using HD Tach 3.01’s 8MB zone setting.

Our ATA performance tests yield few surprises, as the SN21G5 keeps up with the competition. CPU utilization scores are well within HD Tach’s +/- 2% margin for error in that test, as well.

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.

The SN21G5’s Serial ATA performance is right where it should be, although it’s interesting to note that both XPC systems have slightly higher access times than our ATX platforms.

USB performance
Our USB transfer speed tests were conducted with a USB 2.0/Firewire external hard drive enclosure connected to a 7200RPM Seagate Barracuda 7200.7 hard drive. We tested with HD Tach 3.01’s 8MB zone setting.

USB read speeds are a little slow on the SN21G5, which is surprising considering that NVIDIA’s usually pretty solid in that department. The SN21G5 does boast the lowest CPU utilization during our USB transfer rate tests, though.

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

The SN21G5 rips through our Firewire tests, posting higher write speeds than any other platform.

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 4,0,192.168.1.25 -a

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

ntttcpr -m 4,0,192.168.1.25 -a

Our server was a Windows XP Pro system based on Asus’s P5WD2 Premium motherboard with a Pentium 4 3.4GHz Extreme Edition (800MHz front-side bus, Hyper-Threading enabled) and PCI Express-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.

It’s almost embarrassing to watch the SN21G5 limp through our Ethernet throughput tests. The XPC is stuck way at the back of the pack with ECS’s KA1 MVP, which at least has an additional Gigabit Ethernet chip on board. Sadly, the SN21G5 doesn’t have the luxury of a secondary Ethernet option.

Slow transfer rates don’t demand too many cycles, so the SN21G5 at least gets away with the lowest CPU utilization of the lot. Still, we’d gladly swallow the A8N32-SLI’s extra 4% CPU utilization for a 1000% boost in throughput.

Overclocking
For our overclocking tests, we swapped out our Corsair 1GB DIMMs for a pair of 512MB OCZ Platinum Rev 2 memory modules. These particular DIMMs use Samsung TCCD chips and have proven to be solid overclockers in the past, making them perfect fodder for this round of tests.

As usual, we began our overclocking testing by dropping the CPU and HyperTransport processor link multipliers and raising memory timings to 2.5-4-4-8 with a 1T command rate. Then we started turning up the HT clock, easily making it up to 220MHz with no complaint. But the SN21G5 would go no further. The system wouldn’t post with a 225MHz HT clock, and no amount of voltage or memory timing tweaking helped. We also tried lowering the memory bus speed, but that didn’t work. Neither did swapping in different DIMMs.

Small form factor systems have never been particularly adept overclockers, so the SN21G5’s 20MHz HT overclock isn’t that surprising. To its credit, the system was rock solid with a 220MHz HT clock. To see how much performance an extra 20MHz could buy, we upped the CPU multiplier to 11 and ran a few tests. Memory timings were set to 2.5-4-4-8-1T for both the stock and overclocked configs.

In addition to running a faster HT and memory clock, our overclocked config’s processor is also running 20MHz faster than a standard Athlon 64 FX-53. That combination yields modest performance gains in both Far Cry in Sphinx, but nothing spectacular.

Conclusions
It’s been a while since we’ve reviewed one of Shuttle’s XPC systems, and in many ways, not much has changed. That’s not necessarily a bad thing in some respects, since the G5 chassis and ICE cooler are still effective designs that competitors have yet to effectively match. However, it’s a little alarming that the SN21G5 doesn’t really advance the small form factor platform at all. In fact, the system’s lack of Gigabit Ethernet, High Definition Audio, DVI, and TV output actually turn back the clock a little. All of those features could have been present had Shuttle opted for NVIDIA’s GeForce 6150 and nForce 430 combo and a better audio codec instead of the GeForce 6100/nForce 410 pair and an AC’97 codec.

Of course, better chips would make the SN21G5 more expensive. As it is, Shuttle expects this barebones box to sell for $330 or less online. That’s cheaper than other XPCs, although surprisingly, not by all that much. The ST20G5, for example, currently sells for as little as $345. That system comes with Gigabit Ethernet and DVI output, so it’s certainly worth the extra scratch.

As it stands, the SN21G5’s price will have to drop well below $330 for it to become a truly attractive alternative to the ST20G5. Shuttle intends the SN21G5 to be a budget offering, I suppose, but $330 is still way out of reach for most budgets. It seems unlikely that many price-sensitive consumers would even be considering small form factor systems, anyway. After all, you can get a pretty sweet ATX or even Micro ATX motherboard, power supply, and case for well under $300.

The SN21G5 really isn’t more than the sum of its parts, and some of those parts are little behind the times. That makes the SN21G5 difficult to recommend, especially when Shuttle has other XPCs that offer a more attractive suite of features and comparable performance at little extra cost.