When the Shuttle Company offered us their new KT400 based mainboard, called AK37GTR, we were quick to agree. Shuttle AK37GTR does deserve a closer look. Although this mainboard seems quite ordinary, it has certain important advantages over competitor products. At least, they claim it has. It features four DIMM slots while competitor mainboards have only three. That's the first thing. Secondly, it boasts a quality CPU and memory power supply circuit, which should tell on its overall stability. These peculiarities give Shuttle AK37GTR all chances of being among the first in terms of quality.

As we didn't review too many Shuttle products before, however, we are going to make up for it now. Especially since AK37GTR may turn to be the best of all today's VIA KT400 based mainboards. Anyway, we don't feel like making any other preliminary conclusions, let's take a closer look at our today's piece and see everything with our own eyes. We know what we can expect, so now it's up to the mainboard itself to stand up to our hopes.

Before we pass over to the mainboard itself, let's say a few words about the company. In the beginning Shuttle couldn't boast any extraordinary successes and quite naturally was referred to as a third-tier mainboard maker. But not so long ago the company changed its strategy and started growing in popularity. This change of course happened after Shuttle started producing barebone Small Form Factor PCs of the XPC family. Those cute boxes with various stuff inside were a success among both end-users and OEM PC makers.

But what about mainboards? As we see, Shuttle didn't give up this field and now we are going to find out what the present-day mainboards from Shuttle are like. So, here it is on our lab desk: Shuttle AK37GTR.

Specifications

Shuttle AK37GTR
Supported CPUs	AMD Athlon XP/Athlon/Duron (333/266MHz FSB, Socket A)
Chipset	VIA KT400 (VIA VT8367 + VIA VT8235)
FSB frequencies	100-200MHz
Overclocking friendly features	CPU clock multiplier adjustment Vcore, Vmem, Vagp and Vio adjustment
Memory	4 DDR DIMM slots for DDR400/DDR333/DDR266 SDRAM To involve all memory slots Registered DIMM should be used
AGP slot	AGP 8x
Expansion Slots (PCI/ACR/CNR)	5/0/0
USB 1.1 ports	0
USB 2.0 ports	6
IEEE 1394 ports	None
ATA-100/133	+/+
SerialATA-150	2 channels (2 Marvell 88i8030 bridges)
Integrated IDE RAID controller	HighPoint HPT372
Integrated Sound	6-channel AC'97 sound controller: Realtek 650 with SPDIF support
Integrated LAN	10/100Mbit Ethernet (VIA Tahoe VT6103 controller)
Additional Features	None
BIOS	AwardBIOS v6.00PG
Form-Factor	ATX, 305x245mm

Shuttle AK37GTR may come in several variants differing in availability of certain integrated features. There are two variants available now:

• Shuttle AK37GTR - the full version;
• Shuttle AK37GT - without IDE RAID controller and SerialATA support.

The mainboard is accompanied with a usual set of cables and software, as well as with:

• An extra SerialATA cable;
• A back panel bracket with a pair of additional USB 2.0 ports;
• A back panel bracket with audio outputs to the central loudspeaker and subwoofer.

Closer Look: Features

Big things come first. The main advantage of Shuttle AK37GTR, the one we have mentioned in the introductory part, is the four DDR DIMM slots. Thus, the mainboard supports up to 4GB of memory. There is one peculiarity, though: all eight memory banks can only be used with registered DDR DIMM modules. This is a restriction brought about by the VIA KT400 chipset. That's why if you use four ordinary unbuffered memory modules, at least two of them must be single-bank ones.

As for memory types supported, Shuttle imposes no limitations here. According to the official specs, AK37GTR can work with DDR333 and DDR266 SDRAM as well as with DDR400 SDRAM. Well, the last type is supported unofficially as VIA has withdrawn its announcement concerning DDR400 SDRAM support in VIA KT400. There is also one more thing to mention. DDR266 and DDR400 SDRAM can be used in Shuttle AK37GTR only if the processor bus is clocked at 200 or 266MHz. If the CPU bus is clocked at 333MHz, the only memory type allowed is DDR333 SDRAM. These again are peculiarities of the VIA KT400 chipset, which was developed with no implied support for Athlon XP CPUs working with 333MHz bus. In all appearance, VIA is going to fix that problem in its upcoming chipset revision, VIA KT400A.

As for supported CPUs, Shuttle AK37GTR can accommodate without any problems (our tests prove that) Athlon XP with both 266MHz bus and 333MHz bus.

It's also clear that the Athlon XP based on the Barton core with 512KB L2 cache, which is to arrive in the beginning of 2003, will also work with Shuttle AK37GTR. But seems like Shuttle will have to introduce a new BIOS version as the mainboard is already unstable working with Athlon XP 2800+, although it's all right with Athlon XP 2700+. The thing is that the newest Athlon XP CPU is not supported by the current BIOS.

In the MSI KT4 Ultra Mainboard Review we said that today's mainboards targeted at the experienced user share a common feature set. Shuttle AK37GTR is rather an exception from the rule. No, it doesn't feature anything too extraordinary. On the contrary, the manufacturer somewhat shortened the list of its supported features compared to the products of the leading mainboard makers for the DIY sector. For example, Shuttle AK37GTR has no IEEE1394 ports. But overall, the mainboard has usual features.

Thus, Shuttle AK37GTR supports AGP 8x graphics cards as VIA KT400 allows it. Let's remind you, that the chipset has no backward compatibility with the old 3.3V graphics cards, which even can damage the AGP 8x mainboards if installed. However, Shuttle took care of AK37GTR's secure functioning in this case, and introduced a protective system, which simply prevents AK37GTR from booting up with a "wrong" graphics card installed.

Among the mainboard features that are provided by the chipset, there is six USB 2.0 ports support. These ports are managed by hubs integrated into the VIA VT8235 South Bridge. Well, there will actually be only four of them when you buy the mainboard. In order to get all six ports, you will have to buy an additional bracket with two corresponding connectors and cables.

Now let's check the controllers integrated into Shuttle AK37GTR. IDE RAID and SerialATA support seem to be most interesting to us here.

As we see, Shuttle chose the HighPoint HPT372 controller for the implementation of IDE RAID features. The chip has certain advantages over the integrated solutions from Promise. In particular, it supports not only 0 and 1 RAID, but also 0+1. The two Parallel ATA connectors, situated close to the controller, allow connecting and uniting into RAID up to four ATA-100/ATA-133 devices at a time.

But this certainly not the only thing you can do in terms of connecting additional hard drives to the integrated HPT372 controller. Beside every Parallel ATA connector onboard there is a SerialATA connector and a Marvell 88i8030 chip. The chip is a ParallelATA-to-SerialATA converter bridge and thus allows connecting SerialATA devices to the HPT372 controller. So, although the maximum number of IDE-devices the HPT372 chip can handle remains four, two of them can be connected via SerialATA interface. That's how this perspective interface is implemented in Shuttle AK37GTR.

Six-channel sound is made via Realtek ALC650 codec, which is one of the most well-balanced solutions today. It supports SPDIF and produces six-channel sound of acceptable quality. On the whole, although Shuttle decided to use AC'97 and not a PCI sound controller, it chose the best one available.

Shuttle AK37GTR features 10/100Mbit Ethernet implemented in the chipset and an extra interface chip, VIA Tahoe VT6103.

To sum it all up, the features list of Shuttle AK37GTR isn't that huge and took us not too much time to describe. But the next section of our review is going to be much more fascinating for sure.

Closer Look: Design

Of course, we will once again start with pointing out the four DIMM slots of Shuttle AK37GTR mainboard. But now we will take a slightly different look at them. Having laid out four memory slots on the mainboard, Shuttle had to make sure that they would work without any problems. So the main task for the developers was to guarantee sufficient power supply of the components. The four DDR memory modules can consume up to 15W. At the moments of peak workloads, the number can even reach up to 30W. A good power supply is also necessary for high-end Athlon XP CPUs. So, the power supply circuit of Shuttle AK37GTR attracted our attention most.

And we were not disappointed. Shuttle AK37GTR does feature a high-quality power supply regulation circuit. It is based on the Intersil HIP6301CB chip and uses three phases, with two field transistors and toroidal inductance for each phase. Such scheme is most effective and guarantees very "pure" signal.

Shuttle didn't stop there, though. In order to increase the mainboard stability under high workloads, the engineers added the possibility to use 12V power supply besides the ordinary 3V and 5V ones, as it has been done in Pentium 4 mainboards. Besides the ordinary ATX connector, there are two 12V power supply connectors (for ATX 2.03 power units and ordinary ones) that ensure better stability, when the board works under high workloads. That's why we recommend using additional 12V power supply along with the ordinary one, when your system is equipped with powerful processors and several memory modules.

A somewhat unusual placement of the voltage regulator affected the overall mainboard design. Socket A appeared shifted a little to the center of Shuttle AK37GTR, but it results in no inconveniences. There is a lot of free space around the CPU slot that allows easy CPU installation and mounting of both standard and massive cooling systems. Moreover, there are four mounting holes around Socket A, which can come in handy when mounting some overclocker cooling systems.

On the whole, the Shuttle's mainboard is a little larger than usual, although there are fewer additional chips. That's why all the components sit rather free and provoke no collisions. Thus, the DIMM slot clips are not blocked by AGP graphics cards (well, it's also due to Shuttle AK37GTR having only five PCI slots) and the power supply connectors rather nicely sit along the right side of the PCB.

At the same time, there are a few drawbacks in Shuttle AK37GTR design. For example, the AGP slot has no usual clip so modern graphics cards that wear a massive cooling system can just fall out of the slot.

But the most upsetting thing about the design is different. If you look closely at the DIMM slots, you will notice that they are situated too close to each other. Usually, mainboard makers place memory slots at a distance of about 1mm. So if you use several memory modules in Shuttle AK37GTR, their cooling might be hindered a lot, especially if the modules have heatsinks. In the latter case, the modules almost touch each other and there is no air circulation between them.

The North Bridge of the chipset is equipped with pin heatsink without a fan, which is often used by other mainboard makers, but it seems to be quite enough for appropriate heat dissipation from the chip.

One more poke to the Shuttle's side: they don't use the built-in thermal diode to measure CPU temperature. The mainboard has a thermistor installed in the center of Socket A and this is how the overall hardware monitoring of Shuttle AK37GTR controls the processor temperature. As a result, the CPU temperature measurements are inaccurate and inertial.

BIOS and Overclocking

The BIOS in Shuttle AK37GTR is based on the ordinary AwardBIOS v6.00PG micro-code. Setup doesn't appear highly outstanding, either. There are two important advantages, though: the ability to fine-tune timings and numerous overclocking options.

All the memory timings settings are available on a separate page in Shuttle AK37GTR BIOS Setup. Here is a snapshot of the page:

As you see, there is a complete set of options including memory bus frequency modification as well as tweaking of key timings: CAS Latency, Trp, Tras, Trcd and DRAM Command Rate. As for the rest, they are quite useless in BIOS Setup as their modification doesn't affect the system stability, while reducing performance. As Shuttle AK37GTR should demonstrate high stability, as has been mentioned above, we tested it with most aggressive timings and with six memory banks involved simultaneously, that is, in the "hardest" mode for the mainboard. The memory modules we used were 256MB XMS3200 CL2 ones from Corsair.

The mainboard proved absolutely to our expectations. With six banks involved, AK37GTR showed absolutely stable work with both: 166MHz and 200MHz memory bus. Note, that the most aggressive settings for VIA KT400 with 166MHz memory bus are 2-2-2-6-1 (CAS Latency - RAS Precharge - RAS-to-CAS Delay - RAS Active to Precharge - Command Rate), and with 200MHz memory bus - 2-2-2-8-1.

Unfortunately, BIOS Setup of Shuttle AK37GTR doesn't show some timings correctly. The BIOS Setup messages are intended for DDR266 and don't change when you use something else. So we considered it would be helpful to have a table of correspondences for BIOS Setup messages in Shuttle AK37GTR and the actual values.

Note, also, that at 166MHz FSB and up, KT400 based mainboards can only clock the memory synchronously with the FSB. Although you can still choose among DDR266, DDR333 and DDR400 in BIOS Setup, this opportunity in fact doesn't work.

We saw in our MSI KT4 Ultra Mainboard Review that that mainboard allowed setting CAS Latency to 1.5. We see it here again, and again it doesn't work.

As for hardware monitoring, Shuttle AK37GTR can keep track of CPU and system temperatures (the first is taken via an external thermal diode), rotation speeds of three fans and nine different voltages. CPU overheat protection is implemented way too simply in Shuttle AK37GTR: after a certain critical temperature is reached, the system shuts down.

But the opportunities for overclocking are numerous. The positioning of the mainboard for enthusiastic users tells here a lot.

Well, here is the list of the overclocking options the mainboard offers:

• Bus frequency adjustment. The frequency lies in the range between 100 and 200MHz. We should note, though, that the allowed maximum is not that high for today;
• CPU frequency multiplier adjustment from 5.5x to 18.0x.
• PCI frequency divisor adjustment. The possible values (besides Auto): with 100-132MHz FSB - FSB/3 or FSB/4; with >133MHz FSB - FSB/4 or FSB/5. Although overclockers might want FSB/6 divisor, too, it's not supported by the VIA KT400 chipset.
• Processor Vcore adjustment. Besides the default value, you can set any value from 1.0V to 1.85V with 0.025V increment. This quite a good range, although today's CPUs with 1.65V nominal Vcore only allow increasing their voltage by 0.2V.
• DDR DIMM slots voltage adjustment. The range is 2.5V - 2.85V with 0.05V increment. So, Shuttle AK37GTR offers rich options for memory voltage control.
• AGP voltage adjustment. The values possible are Default, 1.6, 1.7 and 1.8V.
• Chipset voltage adjustment. The possible values are: Default, 2.6, 2.7 and 2.8V.

Our practice proved that all the FSB frequencies are functional in Shuttle AK37GTR. Moreover, with 200MHz FSB, the mainboard works stably without increasing any voltages. Well, we have to admit once again that high stability is a definite advantage of Shuttle AK37GTR.

Unfortunately, the mainboard doesn't allow increasing FSB frequency above 200MHz. There would be no problems if it did. The decision of Shuttle engineers to limit the FSB frequency by 200MHz looks even stranger as the ICS94228 clock generator they use in AK37GTR can in theory produce values up to 233MHz. Well, let's hope that the FSB frequency range will be widened in future BIOS versions.

One more sad thing about Shuttle AK37GTR is that you can't reset CPU settings if it gets over-overclocked. So, if the system doesn't power up after some BIOS modifications, the only way to reanimate it is to use Clear CMOS jumper.

Performance

Before turning to the actual benchmarks results, let's mention that mainboards based on the same chipset don't greatly differ in their performance. So when deciding on a particular mainboard, you should pay special attention to rich features, overclocking options, stability and reliability, and technical support rather than its performance in benchmarks.

In our tests we compared Shuttle AK37GTR performance with that of ASUS A7V8X and MSI KT4 Ultra (the two are also based on the VIA KT400) and of the legendary EPoX EP-8K3A+ based on the VIA KT333. Benchmarks were run with different memory types and two Athlon XP CPU models that work with 266MHz and 333MHz bus.

The testbeds were as follows:

• AMD Athlon XP 2700+ (333MHz bus) and AMD Athlon XP 2600+ (266MHz bus) CPUs;
• ASUS A7V8X, EPoX EP-8K3A+, MSI KT4 Ultra and Shuttle AK37GTR mainboards;
• 2x256MB DDR400 CAS2 Corsair XMS3200 and 512MB DDR400 SDRAM by Samsung;
• NVIDIA GeForce4 Ti4400 graphics card;
• Seagate Barracuda ATA IV, 80GB HDD.

Here are the results obtained:

There's no need to comment: the diagrams are explicit. We would only like to note that Shuttle AK37GTR was a little slower than other mainboards. The gap isn't crucial, though.

Conclusion

Shuttle AK37GTR proved up to our expectations and we can crown it as one of the most stable platforms for Socket A processors today. Thanks to high-quality and very smart power supply circuit, the mainboard works well at any FSB frequency and with any memory type.

Shuttle AK37GTR displays a rich set of options for CPU overclocking while its high stability will also prove handy in this case.

There are good options for an upgrade as well. Four DIMM slots are a rare thing to see in Socket A mainboards, and AK37GTR boasts it. There are also five PCI slots, integrated sound, IDE RAID, SerialATA support and an integrated network controller. All this makes Shuttle AK37GTR an excellent solution for a high-performing home or office PC.

Highs:

• The support of the new Athlon XP CPU with 333MHz bus;
• Highest stability, including overclocking;
• High-quality power supply regulation circuit;
• Modern technologies, including USB 2.0, SerialATA and IDE RAID;
• Four DDR DIMM slots.

Lows:

• No support of the thermal diode built into the CPU.

Instead of a P.S.

This is the second of review on our site dealing with mainboards based on the VIA KT400 chipset. But there is one thing you need to know. As we have learned recently, VIA was getting ready for the launch of the KT400 revision. It's KT400A that will feature improved performance and fully-fledged 333MHz CPU bus support. So it seems like the lifecycle of KT400 and mainboards based on this chipset will be rather short. First VIA KT400A based mainboards may hit the market before the end of this year. So if you are going to buy a top-end high-performing Socket A mainboard, keep in mind that the KT400 chipset may not be the best choice due to its short lifecycle.