Foxconn A78AX-S and abit AX78 - value motherboards on the AMD 770 chipset

Together with the top-end 790FX chipset, AMD has released two more versions, somehow cut-down: 790X and 770. Since they are built on the same architecture, it makes sense recalling the major traits of this series. Above all, the chipsets offer support for the HyperTransport v3.0 bus with the frequency 2600 MHz (the maximum bandwidth equals 20.8 GB/s). Today's Phenom processors use the HT frequency with the bus bandwidth being 16 GB/s, so the chipsets still have some "margin". In other words, motherboards based on the 7th series of AMD chipsets are compatible with future AMD Socket AM2+ processors, and their life span is long enough.

Secondly, the listed chipsets offer support for the PCI Express v2.0 bus whose bandwidth is two times as much than that of PCI-E v1.0. That means the performance of two video cards in the Crossfire in the 8+8 configuration is on par with the 16+16 configuration on the previous generation of AMD chipsets. Therefore, unless a joint operation of three or four video cards is planned, the 790X chipset is a perfect match for the Crossfire mode.

We now move on to the AMD 770 chipset. Basically, its architecture meets the top-end chipsets 790FX and 790X, except one point - one PCI Express bus controller is disabled (quite possibly, on the software level). So this chipset supports only one graphic port of PCI Express v2.0 to which 16 bus lanes are allocated. This product is aimed at value discrete systems (i.e., cheap computers without integrated graphics).

We have got two motherboards built on this chipset: Foxconn A78AX-S, and abit AX78 which make quite a big difference from one another. Even the south bridge is different in these motherboards!

By the way, originally chipsets of the 7th series were equipped with the south bridge SB600 which turned outdated still a year ago. Therefore, with the advent of modern SB700, all the manufacturers de-factor switched to using it. It is even used in value motherboards based on AMD 780G which offer a really wide functionality and high performance in 3D applications.

Specifications

Retail boxes

We received the Foxconn board for tests in a ready package and with a full package bundle. As regards the abit product, we received only the motherboard. However, proceeding from our experience, we can infer that the package bundle of the boards will be scarce. However, we should keep it in mind that both the motherboards relate to the value sector, and their package bundle fully meets the retail price.

Package bundle

• motherboard;
• User's Manual in English + brief usage guide;
• Software & drivers CD;
• one ATA-133 cable, one FDD cable;
• 1x SerialATA cable + a power supply adapter (1 connector);
• a cap for the rear panel of the housing.

In practice, it turned out the way we expected: the package bundle of the Foxconn board contains only the most required items. These are the user's manual (+ a brief guide on system assembly), a CD with drivers and software,

ParallelATA and FDD cables, one SerialATA cable with a matching power supply adapter, as well as a cap to the rear panel of the housing.

Layout, expansion options

At first glance, it seems that the abit AX78 board is in many ways superior to Foxconn A78AX-S. In particular, it offers more DIMM slots, more PCI Express x16 slots, and its cooling system includes massive radiators not only on the bridges of the chipset but on the power converter as well. However, the Foxconn board has an ace of trump in the sleeve - installed south bridge SB700, whereas the abit board offers the outdated SB600. Who will win?

Let's start with the cooling system. Since the north bridge of AMD 770 is made following the 65-nm process technology, its heat emission does not go beyond the reasonable limits, even on the overclocking mode. In the end, the engineers have confined to installation of radiators of modest size.

As regards the memory subsystem, two slots are quite enough for an average system with 2 GB installed. But four slots allow for a more flexible control over the memory capacity (e.g., you can add a couple of 512 MB modules to the already installed 2 GB).

As regards the PCI Express x16 slots, in any case two slots is better than one. Even if you don't plan using the CrossFire technology (don't forget that the boards are aimed at the value sector), it is always possible to install one more video card and, if necessary, to plug in four monitors. We should also note that only four PCI Express v2.0 bus lanes are allocated to the second slot. It turns out that the abit board supports the CrossFire and offers a good performance level, since the bandwidth of PCI-E v2.0 is twice as high than that of PCI-E v1.0.

Besides the PCI-E ?16 slot, the Foxconn board uses two more PCI Express x1 and three PCI slots. The abit board offers fewer additional slots: one PCI Express x1, and three PCI slots.

Then, the Foxconn board uses the SB700 south bridge with a radiator. In the end, the board supports 6 SerialATA II and one ParallelATA links. The abit board also supports one PATA link, but since it uses the outdated SB600, the number of SATA links = 4.

In the end, eight hard disks can be plugged in to the Foxconn board (six SATA II and two PATA), while only six hard disks (four SATA II and two PATA, respectively) to the abit board.

Then, the south bridge SB700 supports 12 USB 2.0 ports (plus a couple of USB 1.1 ports). However, on the Foxconn board there are merely ten ports wired: for external and six additional. Quite possibly, Foxconn uses one PCB to produce motherboards with both SB700 and SB600. The latter supports only ten ports, and engineers at abit have wired them following the same scheme: 4+6.

As regards the audio subsystem, the abit board implements the 8-channel HD-system based on the ALC888 codec. The same codec is installed on the Foxconn motherboard.

Now a few words on the network support: both the motherboards use a high-speed Gigabit Ethernet LAN controller. On the Foxconn board, that is the Realtek RTL8111B chip, on the abit board - a Marvell 88E8056 chip.

The board's rear panel is of the following configuration:

On the Foxconn board, there is one parallel and two COM ports. Instead of these outdated interfaces, the abit board uses only the optical SP-DIF output, as well as a switch to clear the CMOS.

Note that on the abit board there is a 7-stage POST indicator.

Here is the components layout of the abit board (we were unable to find such a layout for the Foxconn board).

Now on to the BIOS settings.

BIOS, monitoring, overclocking tools

The BIOS of Foxconn A78AX-S is based on the AMI BIOS version, while the BIOS of the abit board - on the Award BIOS Phoenix version.

We start with the memory settings. Both the boards provide the user with a really wide selection of latency timings:

As regards the setting of memory frequency, both the boards allow setting any available frequency supported by an AMD processor (since the memory controller is integrated into the CPU).

Now look at the system monitoring section.

At this part, the abit board takes a lead, which not only determines the temperature of the CPU and the system, but also the temperature of the power converter. Besides, the abit board keeps track of the rotational speeds of the four fans versus two in the Foxconn board.

Besides, the boards support the feature for dynamic adjustment of the rotational speed of the two coolers depending on the temperatures of the CPU and the system.

Overclocking and stability

Before we move on to overclocking, let's look at the power converters. The PWM of the abit board uses a 4-phase scheme in which there are eight 680 mkF and four 1000 mkF capacitors. The PWM of the Foxconn board uses a 4-phase power scheme, in which there are eight 1800 mkF and four 1000 mkF capacitors.

Note that on the power components of the PWM of the abit board there is a separate radiator which is linked to the radiator of the north bridge with a heat pipe.

Now on to the overclocking features.

To start with, the Foxconn wouldn't overclock the CPU at all: a raise of the HTT frequency by even 4 MHz immediately resulted in the system hang. As regards the abit board, its result proved lower than the average - the maximum stable HTT frequency = 280 MHz (and up to 266 MHz the system was running with the nominal voltage levels).

However, we should note that the boards used the pre-release version of the BIOS, so we are sure that future firmware updates will improve the situation with overclocking.

Performance and conclusions

It turned out that while determining the starting HTT speed, both the boards set it at an ideal precision.

In our test setup, we used the following hardware:

Let's first take a look at the results of synthetic benchmarks.

Now on to the gaming benchmarks.

The performance of the motherboards is absolutely identical, and the only thing that surprised us is that the results for 3DMark 2001 proved to be lower than the results for 3DMark 03.

Final Words

Both the boards fall within the value sector and indeed offer quite an affordable price. At least, abit AX78 is already available at the Moscow retail at a price about ~$80. The price for Foxconn A78AX-S is still unknown, but we believe it should also be at about $80. The thing is that there is even the Foxconn A78AX-K model (~$70) which differs from the -S modification by the cheaper 6-channel audio subsystem.

But which motherboard is better? From the seller's viewpoint, the best buy is the Foxconn motherboard since it offers the more improved south bridge SB700. And it costs a bit less, which is really important for buyers of AMD systems who save on every dime. From the buyer's viewpoint, the abit board is better. Although it costs $9 more, it uses the outdated south bridge. On the other hand, it gives more freedom in configuring the system: it offers more DIMM slots, two slots for installation of PCI-Express video cards, better cooling system, and functional overclocking tools.

As regards the package bundle, we haven't yet got the data on the box contents of the abit motherboard. The package bundle of the Foxconn product fully meets the price.

Conclusion