Today we will once again talk about the Small Form Factor PC concept. And we would like to point out first that the system to be reviewed today is quite different from the recently-tested small form-factor barebone system from FIC (see our Samba(SM)-1845: Small Form-Factor PC from FIC article).

The thing is that advanced users became interested in SFF PCs, although initially they were targeted at unsophisticated users for work with office applications, surfing the Web or watching video at home or office. Well, it's really convenient to have a noiseless and stylish-looking system case rather than a big and roaring desktop PC. Of course, such solutions with pretty small dimensions are not universal, but many users would feel quite happy with a PC featuring a powerful CPU, an AGP graphics card, one HDD, one optical drive and only one expansion card. So, the small but powerful SFF PCs have their guaranteed niche in the market.

So, there appeared manufacturers willing to occupy this vacant niche. Especially, as the whole semiconductor industry is suffering a long-time crisis and companies search for more opportunities to sell their products.

The Shuttle Company was the first one to start producing powerful SFF PCs and to succeed in this filed. We should note that although the barebone PCs from Shuttle may be used for rather high-performance computers, they are also positioned as competitors to the classical Small Form Factor PC for home and office.

So, let's have a look at SFF PCs from Shuttle. They do break all our presuppositions about small and noiseless computers. For this review, Shuttle provided us with two top-end configurations: for AMD Athlon XP and for Intel Pentium 4 CPUs.

Specifications

The two Small Form Factor PCs from Shuttle, which we've got into our test lab, are SK41G and SB51G (their common name is XPC). They support different processors and differ a lot by their specs. So, let's discuss them one by one.

The first barebone PC reviewed here is Shuttle SB51G. It supports Socket478 Intel Pentium 4 and Intel Celeron processors that work at 400MHz or 533MHz system bus. The system is built on the integrated i845GE chipset from Intel. It supports external AGP 4x graphics cards, too. It should be noted that, thanks to the one of the most up-to-date chipsets, SB51G can theoretically work with the top-end CPUs from the Pentium 4 family and fully support the Hyper-Threading technology. This SFF PC also differs from similar products by the available support of high-end DDR333 SDRAM. Note that the ICH4 South Bridge provides SB51G with a lot of useful qualities: from USB 2.0 to networking and 6-channel sound. Shuttle also equipped the mainboard used in SB51G with a few extra chips to add IEEE1394 ports support.

Before we introduce to you the Shuttle SB51G, let's take a look at its package (another SFF PCs from Shuttle come in similar boxes).

This box contains a nice little "cube", which is the new barebone system from Shuttle. In order for you to better understand how big it is, we made a snapshot of it beside a traditional mini-tower from Inwin:

Note that while Small Form Factor PCs from other manufacturers are designed like "thin" rectangles, Shuttle chose the "cubic" shape. This engineering solution has a number of advantages, the main is the opportunity to squeeze in more components. This brick is also stylish-looking, which is emphasized by the translucent plastic that covers the front panel of the reviewed SFF PC. By the way, this plastic can be easily removed to insert some picture beneath. So, the user's got a lot of opportunities to change the look of the "brick".

Here are the specifications of Shuttle SB51G:

• Socket478 CPUs: Intel Pentium 4 and Intel Celeron with 533MHz and 400MHz bus;
• Hyper-Threading technology support;
• i845GE chipset with ICH4 South Bridge;
• Two DDR DIMM slots. Supports up to 2GB of DDR200/DDR266/DDR333 SDRAM;
• One AGP 4x and one PCI slot;
• The integrated graphics core: 256-bit Intel Extreme Graphics;
• Six-channel AC'97 codec Realtek ALC 650 with SPDIF in- and output support;
• An integrated VIA VT6306 IEEE1394 controller;
• One 3.5" internal bay for an ATA/133 HDD, one 3.5" external bay for a standard 1.44MB FDD, one 5.25" external bay for an external ATA/133 optical drive;
• An integrated Realtek 8100B 10/100Mbit Ethernet controller;
• The 200W power supply unit from Achme;
• Four USB 2.0 ports (two are on the front panel and two - on the back panel);
• Three IEEE1394 ports (one is on the front panel and two are on the back panel);
• Dimensions: 82 (width) x 43 (height) x 190 (depth)mm.

The package also includes a cooling system and an optional riser card, which is installed into the AGP slot to implement TV-Out and DVI outputs when the integrated graphics core is used.

Note that Shuttle doesn't ship a 3.5" 1.44MB FDD with its barebone system. Today it's not a necessary part for a computer, thus this may be even regarded as an advantage.

The second barebone system is Shuttle SK41G. It looks a lot like its above-discussed mate. At first sight there seem to be only two external differences: different front panel color and a TV-Out instead of the SPDIF out at the back panel.

But the external similarity conceals quite a different stuffing. Shuttle SK41G is based on the VIA KM266 chipset and supports Socket A CPUs with 200MHz and 266MHz system bus. Unfortunately, Athlon XP CPUs with 333MHz bus are not supported due to chipset limitations. But as there are no integrated chipsets in the market with higher functionality, SK41G will be the top model in the barebone series from Shuttle for AMD processors. Well, this is going to end with the beginning of mass production of the nForce2 IGP from NVIDIA. If we disregard the fact that Shuttle SK41G doesn't support new Athlon XP CPUs and works only with DDR200/DDR266 SDRAM, all the other characteristics of this SFF PC will not be any worse than those of analogous products for Intel processors.

Shuttle SK41G allows using both: the integrated graphics core and external AGP 4x graphics cards. It also has an expansion slot. The up-to-date VIA VT8235 South Bridge supports USB 2.0, LAN and six-channel AC'97 sound. Just like in SB51G, IEEE1394 ports are implemented via an external chip.

SK51G comes in a similar box, which contents doesn't actually differ from that of SB51G. Here is the full list of Shuttle SK41G specifications:

• Socket A CPUs: AMD Athlon XP/Athlon and Duron with 200MHz and 266MHz bus;
• VIA KM266 chipset with VIA VT8235 South Bridge;
• Two DDR DIMM slots. Supports up to 2GB of DDR200/DDR266 SDRAM;
• One AGP 4x and one PCI slot;
• The integrated 256bit S3 ProSavage8 graphics core;
• Six-channel Realtek ALC 650 AC'97 codec with SPDIF output;
• An integrated VIA VT6306IEEE1394 controller;
• TV-Out provided by the Chrontel 7005C chip with PAL and NTSC formats support and in up to 800x600 resolutions;
• One 3.5" internal bay for an ATA/133 HDD, one 3.5" external bay for a standard 1.44MB FDD, one 5.25" external bay for an external ATA/133 optical drive;
• An integrated Realtek 8100B 10/100Mbit Ethernet controller;
• The 200W power supply unit from Achme;
• Four USB 2.0 ports (two are on the front panel and two - on the back panel);
• Three IEEE1394 ports (one is on the front panel and two are on the back panel);
• Dimensions - 82 (width) x 43 (height) x 190 (depth)mm.

Note that TV-Out support is available in the standard Shuttle SK41G configuration, while DVI output cannot be implemented by the integrated graphics core in this system.

Closer Look

As the both "cubes" look very similar to one another, we will talk about both of them at a time here.

Shuttle SB51G (left); Shuttle SK41G (right)

The front panel of the both SFF PCs carries two USB 2.0 ports, an IEEE1394 port, a headphones output, a microphone input and an optical SPDIF output. There are also Power-on and Reset buttons. Besides, there are two brackets that cover front sides of the bays where the 3.5" FDD and 5" optical drive may be installed. We should note, though, that if you install into the bay a device with an "output", the stylish color palette of the front panel would be somewhat disturbed, because the external part of the bays is not covered by any lids or the like as in barebones from other manufacturers.

Shuttle SB51G (left); Shuttle SK41G (right)

Let's come up to Shuttle SK41G and SB51G from behind. Besides the power supply connector, the back panel carries two serial ports, a video output for the integrated graphics core, two IEEE1394 connectors, two USB 2.0 ports, an RJ45 connector for network, six-channel audio outputs and PS/2 connectors for the mouse and keyboard. Moreover, SK41G features a TV-Out, while SB51G - an SPDIF output. Note that among all this stuff there is no parallel port, so you will have to use USB printers with these Shuttle barebone systems. You can also see two brackets that stand instead of expansion cards, one of which is against the AGP slot and the other is against the only PCI slot. Note that DVI and TV-Outs in Shuttle SB51G may be implemented via a daughter-card plugged into the AGP slot. SK41G doesn't support DVI displays when the integrated graphics core is used.

We would also like to say a few words about the case in which Shuttle integrates its SFF PC or, if you don't mind, XPC. As the company positions its SFF barebone systems somewhat higher than an ordinary noiseless computer, they made the case of pure non-colored aluminum. As a result, the XPC from Shuttle is lighter than competitor products and looks somewhat unusual. It's a known fact that aluminum conducts heat better than traditional steel so, considering the small size of the case, the choice of this material may be of some help for the heat takeoff.

To emphasize the fact that Shuttle SK41G and SB51G are something more than an ordinary barebone system, the company offers a few accessories to make the exterior of the product more unusual. Among them: multicolor plastic covers for the front panel, bulbs to highlight it and a bag to carry the XPC in.

We had at our disposal a luminous cover for the front panel. After we replaced the ordinary panel with the luminous one (it can be done very easily), the XPC from Shuttle served not only as a computer, but also as a desk lamp. :)

The luminous panel package also includes a required inverter as well as a mounting six-rib spanner.

To sum up our overview of the barebones from Shuttle, we have to say that in order to transform the carcass into a fully-fledged computer, you will need a processor, memory, a hard disk drive and an optical drive. Optional are a 3" FDD, an external AGP graphics card and a PCI expansion card.

Mainboard

Now let's take a closer look at the components of our barebone systems. First come the mainboards used in Shuttle SK41G and SB51G. Although the two mainboards support quite different processors, they have got a lot of similarities in their design and functions. This is largely due to the peculiarities of the case the mainboards are installed in. We will discuss the mainboards one by one, though. So, first we will look inside Shuttle SB51G, where we find the mainboard for Socket478 CPUs.

This barebone system is built on FB51 mainboard also manufactured by Shuttle. Although this mainboard was developed specifically for SFF PCs, it can be purchased separately, too.

FB51 is a very compact product based on the i845GE chipset with ICH4 South Bridge. As you know, i845GE is the integrated version of the new Intel's chipset, i845PE, with an integrated 266MHz Intel Extreme Graphics core.

The North Bridge provides support for AGP 4x slot and DDR memory (there are two 184-pin DIMM slots onboard). Shuttle FB51 is compatible with all Socket478 processors from Intel, the new Pentiums 4 with the Hyper-Threading technology included. As for memory clock-rate, it is set in BIOS Setup at 200, 266 or 333MHz depending on the type of memory used.

Shuttle FB51 is equipped with an external AGP 4x slot and one PCI slot. The upgradeability of the product ends here. But considering the number of integrated controllers onboard, these two slots must be quite enough. Moreover, the AGP slot may serve either for graphics subsystem upgrade or for the implementation of additional DVI and TV outs with the help of a special riser card.

As for the PCI slot, the only application for it that comes to mind is installation of a modem. An average user just won't need anything more in an FB51-based system. Just look: the mainboard has six USB 2.0 ports implemented in ICH4 South Bridge (Shuttle SB51G case has four ports), three IEEE1394 ports (VIA VT6306 controller), a network Realtek RTL8100B controller, a six-channel AC'97 sound (Avance Logic ALC650 chip) and two ATA/100 channels support.

As we mentioned above, the XPCs from Shuttle lack a parallel port, but the mainboard itself isn't the one to blame. This port has been laid out on it, but there was simply no place at the back panel of the PCB to place it. As a result, this port is available via an external connector, attached to the onboard connector. The external connector is not included into the shipment package, but can be ordered optionally.

We should also point out to you that the FB51 mainboard boasts a few features, which cannot be found in Shuttle SB51G SFF PC. For example, the mainboard allows connecting an infrared port through a special socket. The port itself is not designed in the "cube".

Shuttle FB51 mainboard has no jumpers, except Clear CMOS. No wonder as it is installed into small cases where you can hardly get inside. So, the configuration of the integrated devices is done via BIOS Setup, which is based on the Award BIOS 6.00PG code.

The BIOS of Shuttle FB51 offers certain opportunities for CPU overclocking. Since Shuttle SB51G SFF PC is positioned as a competitor to desktops, this option stands to reason. So, BIOS Setup allows setting the FSB frequency from 100 to 165MHz with 1MHz increment (the 100-132MHz range is for CPUs with 100MHz bus, the133-165MHz range is for CPUs with 133MHz bus). So, some overclockers may come to like the small systems from Shuttle. At the same time, the mainboard used in SB51G has no options for voltages adjustment and AGP/PCI frequency adjustment so this PC shouldn't be regarded as an overclocker's platform after all.

Now, let's have a look at the Shuttle FX41 mainboard, which is used in the barebone system for AMD processors.

The FX41 mainboard is based on the VIA KM266 chipset with the VIA VT8235 South Bridge supporting USB 2.0. As you probably know, the standard configuration of KM266 includes an older VIA VT8233 South Bridge with less attractive features. Today, KM266 is the most up-to-date integrated chipset from VIA for Socket A platforms. This chipset is equipped with the S3 Graphics ProSavage8 core with internal AGP 8x bus support and hardware DVD Motion Compensation support.

Besides the integrated graphics core, the chipset supports an external AGP 4x port of Shuttle FX41. As for the memory, KM266 works with DDR200/DDR266 SDRAM. FX41 is equipped with two DDR DIMM slots for 184-pin memory modules. The memory bus frequency, like in FB51, is set through BIOS Setup, but unlike FB51, FX41 doesn't support DDR333.

The list of supported processors looks limited, too. Shuttle FX41 can only work with AMD Athlon XP, Athlon and Duron CPUs with 200 and 266MHz bus. The new Athlon XP CPUs with 333MHz bus are not supported because of the chipset limitations.

FX41 carries the same integrated equipment onboard as FB51, so there is no need to describe it once again. The only difference is a Chrontel 7005C chip that implements a TV-Out. The DVI-output is not available by FX41.

Funny enough, Shuttle FX41 has not only the standard power supply connector, but also an additional 12V connector that's usually used in Pentium 4 mainboards. But it doesn't mean that FX41 sets any special requirements for the power supply. It's just that the barebone systems from Shuttle intended for Pentium 4 and Athlon XP processors both use the same power supply units.

Like all present-day Socket A mainboards, FX41 features an integrated CPU overheating protection system. If the temperature measured by the external Socket A thermistor is above some threshold value (as set in BIOS Setup), the system shuts down and a special onboard LED lights up indicating that the shut-down has occurred because of overheating.

The BIOS Setup in FX41 offers some overclocking options. Thus, this platform may be considered as a solution for advanced users. The onboard jumper allows changing the basic FSB frequency between 100 and 133MHz. You can further fine-tune it in BIOS Setup: from 100 to 165MHz with 1MHz increment. The BIOS Setup in FX41 also allows adjusting all the main memory timings. From the overclocker's point of view, the FX41 mainboard has two serious disadvantages, though. Firstly, you cannot manually adjust any voltages. Secondly, and it's more important, this mainboard doesn't allow changing the CPU multiplier.

Power Supply Unit

The power supply units are important components of SFF PCs. They should be small and at the same time provide enough power. Both reviewed XPC from Shuttle come with the same power supply unit, which should comply with special requirements. As Shuttle positions its systems for high-end market, this power supply unit must be able to work with most powerful CPUs and graphics cards.

So, the company chose to use in its Shuttle SK41G and SB51G a 200W small-size PSU from ACHME. This should be enough to supply the CPU (up to 100W), the graphics card (up to 50W), the HDD (up to 15W) and all the other system components. It's also handy that this PSU has six cables for connecting various devices, besides the 20-pin cable for the mainboard. After connecting the additional 12V cable to the mainboard, and connecting the HDD, optical drive and FDD, there remain two "tails" left. You can use them for powering a second HDD or a graphics card like ATI RADEON 9700 PRO that requires extra power.

We would like to mention that the power supply unit from ACHME has no ordinary 110V/220V switch. The point is that this PSU can work at any supply line voltage lying within this range without any additional effort on user's part.

There is a small fan in the PSU that serves to cool the internal PSU components.