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[nextpage title=”Introduction”]A790GXM-AD3 is the socket AM3 version from A790GXM-A, which we have already reviewed. It is an ATX-sized motherboard with on-board video based on AMD790GX chipset featuring two x16 PCI Express slots, HDMI output and other interesting features. Let’s take a look at this motherboard.

A790GXM-A, however, features a dedicated 128 MB on-board video memory in order to increase gaming performance (feature called “Side Port”), which is not present on A790GXM-AD3.

Right now AM790GX is the chipset with the fastest graphics engine available, called Radeon HD 3300. It is based on the same engine as AMD780G (Radeon HD 3200), but running at a higher clock rate (700 MHz vs. 500 MHz). It is also faster than the new AMD785G (Radeon HD 4200), which runs at the same clock rate as AMD780G (500 MHz). All these three chips have 40 processing units inside. AMD780G and AMD790GX are DirectX 10 parts, while AMD785G is DirectX 10.1. The second main difference between AMD785G and AMD780G/AMD790GX is the inclusion of more stages on the integrated video decoder and the inclusion of more stages on the chipset integrated video decoder (called UVD, Unified Video Decoder by AMD), which helps increasing performance when playing movies on your PC, since tasks that are traditionally performed by the CPU are now performed by the chipset. Another smaller difference is the support for HDMI version 1.3 on AMD 785G, while AMD780G and AMD790GX support HDMI 1.2.

AMD790GX is paired with SB750 south bridge chip, which provides two differences to SB700 (AMD780G) and SB710 (AMD785G). First the support for RAID 5. And the second, the support for ACC (Advanced Clock Calibration) that allows you to unlock hidden features from certain Phenom processors: depending on the CPU model you can unlock extra memory cache and even one extra CPU core, in the case of triple-core CPUs. You can read more about this feature here and here. So this feature is supported on this motherboard.

Keep in mind that socket AM3 motherboards are compatible only with socket AM3 CPUs. While socket AM3 CPUs can only be installed on socket AM2+ motherboards, you cannot install socket AM2+ CPUs on socket AM3 motherboards. In fact AMD says that this installation will burn the CPU and the warranty doesn’t cover this situation.

A790GXM-AD3 is part of Black Edition series from ECS, where one of the main features is using only solid capacitors. As mentioned it is an ATX motherboard, not microATX like the majority of motherboards with integrated video.

Figure 1: ECS A790GXM-AD3 motherboard.

[nextpage title=”Slots and Memory”]

ECS A790GXM-AD3 motherboard comes with two x16 PCI Express 2.0 slots, two PCI Express x1 slots and two standard PCI slots. When only one video card is used, the main PCI Express x16 slot really works at x16, but when two video cards are installed both slots work at x8.

So A790GXM-AD3 provides a great flexibility in terms of video configuration. You can use its on-board video, you can disable the on-board video and install up to two video cards and you can also enable the on-board video to work in parallel with a video card under CrossFire mode if you install a card that is compatible with Hybrid Graphics technology (read our SLI vs. CrossFire tutorial for a complete list of compatible cards).

A standard peripheral power plug is available next to the main PCI Express x16 slot to provide extra power to the graphics card. ECS doesn’t say exactly when we should use this connector, so it is better if you always keep it installed to the power supply.

Figure 2: Slots.

Socket AM3 CPUs support both DDR2 and DDR3 memories, but the kind of memory you can have depends on the kind of motherboard they are installed on, socket AM2+ or socket AM3, respectively. Being a socket AM3 motherboard, ECS A790GXM-AD3 supports only DDR3 memories. It comes with four memory sockets and in order to achieve the maximum performance possible you need to install two or four memory modules in order to enable the dual channel feature, which doubles the available memory bandwidth. If two modules are used, you need to install them on sockets with the same color. On this motherboard sockets one and two are orange and sockets three and four are yellow.

The maximum amount of memory you can have is 32 GB (by using four 8 GB modules), up to DDR3-1333/PC3-10600.

Figure 3: Memory sockets.

[nextpage title=”On-Board Peripherals”]

SB750 south bridge chip supports six SATA-300 ports allowing RAID 0, 1, 5, 10 and JBOD, and one ATA-133 port. All the SATA ports are located facing the motherboard edge, so the cables on these connectors are installed parallel to the motherboard. Some manufacturers put the SATA ports on the same line as the PCI Express x16 slots and then the video card makes it difficult or even impossible for you to install cables on the SATA ports, problem that does not happen with ECS A790GXM-AD3.

Additionally this motherboard has one eSATA-300 port located on the rear panel, controlled by a JMicron JMB361 chip.

As you can see in Figure 4, A790GXM-AD3 like other members from Black Edition series from ECS has on-board power and reset buttons, which helps a lot if you are overclocking or debugging your PC.

Figure 4: SATA ports.

No floppy disk drive controller is present.

This motherboard has all the 12 USB 2.0 ports supported by the chipset, six soldered on the rear panel and six available through three motherboard headers. The motherboard doesn’t come with I/O brackets for you to use the USB headers, so is interesting to buy a case with four USB ports to go with this motherboard. No FireWire ports are provided.

Audio is generated by the chipset using a Realtek ALC888S codec, which provides 7.1 audio with 24-bit resolution, 97 dB signal-to-noise ratio for the outputs, 90 dB signal-to-noise ratio for the analog inputs, 192 kHz sampling rate for the outputs and 96 kHz sampling rate for the inputs. If you want to work professionally converting and editing audio from an analog source (e.g., converting VHS tapes, LPs, etc to digital format) we highly recommend you to pick a motherboard with a codec with at least 100 dB signal-to-noise ratio (SNR) for its analog inputs (ADC).

This motherboard comes with an on-board optical SPDIF output, and coaxial SPDIF output is supported through an SPDIF out header present on the motherboard. If you want to use this output you will need to buy an I/O bracket containing i
t, as this motherboard doesn’t come with one.

On the analog side ECS A790GXM-AD3 doesn’t come with independent 7.1 analog outputs. You will be able to use a set of 5.1 speakers together with a line in cable and a microphone installed, but if you want to use line in and mic in at the same time as 7.1 audio you will have to use the SPDIF output for that.

A Gigabit Ethernet port is provided, controlled by a Realtek RTL8111C chip.

A790GXM-AD3 comes with an on-board HDMI output. Together with its on-board optical SPDIF output it may be an option to build a home theater PC (HTPC).

In Figure 5, you can see the motherboard rear panel with PS/2 mouse and keyboard connectors, clear CMOS button, VGA and HDMI outputs, six USB 2.0 ports, eSATA-300 port, optical SPDIF output, Gigabit Ethernet port and analog (5.1 independent/7.1 shared) audio outputs.

Figure 5: Motherboard rear panel.

[nextpage title=”Other Features”]

A790GXM-AD3 uses a four-phase voltage regulator and this is a place you may want to consider to take into account when comparing competing products (the higher the number of phases the better, read our Everything You Need to Know About the Motherboard Voltage Regulator tutorial).

Like other new motherboard from ECS, A790GXM-AD3 features a function called eJiffy, which is basically a Linux-based operating system with Internet browser, instant messaging and other features stored inside the motherboard ROM chip, so you don’t need to load the operating system or even have a hard drive installed to enter the Internet and do basic stuff like browsing, e-mail, instant messaging, etc. ASUS has a similar feature on their motherboards, called Express Gate.

In Figure 6, you can see all accessories that come with this motherboard.

Figure 6: Accessories.

[nextpage title=”Overclocking Options”]

ECS A790GXM-AD3 offers some overclocking options. The options present (07/15/2009 BIOS) are:

• CPU base clock: can be adjusted from 190 MHz to 400 MHz in 1 MHz increments.
• CPU voltage: From 0.800 V to 1.550 V in 0.025 V increments.
• CPU voltage (additional configuration): +20 mV to +300 mV in +20 mV increments on top of the above configuration.
• Memory voltage: +10 mV to +150 mV in +10 mV increments on top of the current memory voltage.
• North bridge voltage: +5 mV to +75 mV in +5 mV increments on top of the default voltage.
• North bridge 1.8 V reference voltage: 1.80 V a 2.0 V in 0.1 V increments.
• South bridge voltage: From 1.20 V to 1.35 V in 0.05 V increments.

Memory timings can also be tweaked.

Figure 7: Overclocking menu.

Figure 8: Overclocking menu (Cont’d).

Figure 9: Memory timing options.

[nextpage title=”Main Specifications”]

ECS A790GXM-AD3 motherboard main features are:

• Socket: AM3
• Chipset: AMD790GX + SB750
• Super I/O: ITE IT8726F
• Clock generator: ICS 9LPRS471CKL
• Parallel ATA: One ATA-133 port controlled by the south bridge chip.
• Serial ATA: Six SATA-300 ports controlled by the chipset (supporting RAID 0, 1, 5, 10 and JBOD).
• External SATA: One eSATA-300 port controlled by a JMicron JMB361 chip.
• USB: 12 USB 2.0 ports, six soldered on the motherboard and six available through three headers on the motherboard (the motherboard doesn’t come with I/O brackets for you to use these ports).
• FireWire (IEEE 1394a): No.
• On-board audio: Produced by the chipset together with a Realtek ALC888S codec (eight channels, 24-bit resolution, up to 96 kHz sampling rate for the inputs and up to 192 kHz sampling rate for the outputs, 90 dB signal-to-noise ratio for the inputs and 97 dB signal-to-noise ratio for the outputs). On-board optical SPDIF output.
• On-board LAN: One Gigabit Ethernet port controlled by a Realtek RTL8111C chip, which is connected to the system through one PCI Express x1 lane.
• Buzzer: No.
• Power supply required: EPS12V.
• Slots: Two PCI Express 2.0 x16 slots (both working at x8 when two video cards are installed), two PCI Express x1 slots and two standard PCI slots.
• Memory: Four DDR3-DIMM sockets (up to 32 GB up to DDR3-1333/PC3-10600).
• Number of CDs/DVDs provided: One.
• Programs included: Motherboard drivers and utilities.
• Extra features: Only solid capacitors, eJiffy, external clear CMOS button.
• More Information: https://www.ecsusa.com
• Average price in the US*: USD 110.00 (USD 92.00 after a USD 18 mail-in rebate)

* Researched at Newegg.com on the day we published this First Look article.

[nextpage title=”Conclusions”]

AMD790GX-based motherboards may seem expensive for a product with on-board video. But you have to keep in mind that it does not compete on the same segment as very low-end motherboards with integrated graphics. This happens because it is an ATX motherboard, not a microATX one, featuring two PCI Express x16 slots. Thus this motherboard can be an interesting option for users that are on budget at the moment but plan to upgrade their systems to a high-end gaming system with up to two video cards. Plus their gaming performance is higher than any other chipset with integrated graphics.

The highlights from ECS A790GXM-AD3 include the presence of an HDMI output and on-board optical SPDIF output, making it very easy for you to hook up the computer to your home theater system, and use of solid capacitors.

Places where ECS can improve (and this is valid for most of their products) include the voltage regulator (only four phases), the audio codec (low signal-to-noise ratio for the analog inputs) and the use of 300 different colors on the motherboard, making it to look like a parade float car. On the other hand, EC
S usually brings the most affordable motherboards.