ECS A790GXM-A Black Series is a socket AM2+ motherboard based on the latest chipset from AMD, 790GX. Formerly known as RS780D, this chipset provides on-board video using a new graphics engine (Radeon HD 3300) with a dedicated 128 MB GDDR2 on-board memory (feature called “Side Port” by AMD) and also providing two PCI Express 2.0 x16 slots (running at x8 if both are used at the same time). In this review we will compare the performance of AMD 790GX to AMD 780G and GeForce 8200, and we will also analyze Hybrid CrossFire performance. Check it out.

The new AMD 790GX is basically an overclocked AMD 780G with a new south bridge chip, plus a dedicated 128 MB GDDR2 memory for use as video memory, instead of stealing memory from the system – if the video engine requires more than 128 MB, then it will “steal” the remaining amount from the main RAM. AMD 790GX engine is called Radeon HD 3300, while the engine used on AMD 780G is called Radeon HD 3200.

While AMD 780G is paired with SB700 chip, AMD 790GX is paired with the new SB750 chip, which brings basically two new features: RAID 5 support and a new overclocking feature called “Advanced Clock Calibration” or simply ACC. How exactly this new feature works is completely obscure, as AMD does not explain how it works in details. All we know is that SB750 provides a feedback loop to Phenom processors using some unused CPU pins. This feature is only available on Phenom processors. You can read a little bit more about this feature here.

On the table below we provide a comparison between AMD 790GX and its predecessor, AMD 780G, and also with GeForce 8200.

Other current chipsets with on-board video from AMD include AMD 690V, AMD 690G, AMD 740G, AMD 780V and AMD 780G. AMD 690V, AMD 690G and AMD 740G are based on a DirectX 9 graphics engine, while AMD 780V, AMD 780G and the new AMD 790GX are based on a DirectX 10 one. AMD 780V is based on Radeon HD 3100 engine, which runs at 400 MHz – clock is the main difference between HD 3100, HD 3200 and HD 3300 engines. AMD 780V also doesn’t support Hybrid CrossFire configuration (more about this feature in just one second).

ROPs stand for “Raster Operation Units” and are also known as “Rendering Back-End Units”. They are the final stage on rendering a 3D image.

Both chipsets support Hybrid SLI and Hybrid CrossFire technologies. These technologies allow the on-board video to work in parallel to a discrete video card under SLI or CrossFire modes, increasing gaming performance (usually when you install a “real” video card the on-board video is disabled). The video card must support this technology and in fact only a few support this. Read our tutorial SLI vs. CrossFire for further information.

In this review we will analyze the Hybrid CrossFire feature by installing a Radeon HD 3450 on the reviewed board, first with the on-board video disabled and then with it enabled and CrossFire mode activated.

In our benchmarking we will compare ECS A790GXM-A (AMD 790GX) to  Sapphire PI-AM2RS780G (AMD 780G) and ECS GF8200A Black Series (GeForce 8200).

Before going to our tests, let’s take an in-depth look ECS A790GXM-A.