Biostar TA785GE 128 M is a micro ATX socket AM2+ motherboard with on-board video based on the new AMD 785G chipset, which uses a new DirectX 10.1 graphics engine (Radeon HD 4200, codenamed RV620) featuring dedicated 128 MB video memory on the motherboard (feature called “Side Port” by AMD) to increase performance. In this review we will compare the performance of AMD 785G to AMD 790GX and AMD 780G and we will also analyze Hybrid CrossFire performance. Check it out.

The new AMD 785G chipset can be used on socket AM2+ or on socket AM3 motherboards. On the first case, the system will use DDR2 memories, while on the second it will use DDR3 models. Socket AM3 CPUs can be used on any of the two platforms, depending on what kind of memory you want to use, however socket AM2+ CPUs cannot be installed on AM3 motherboards. In fact AMD alerts that if you try you will fry your processor and they won’t replace it because the warranty does not cover this situation.

This chipset, like AMD 790GX and 780G, has as an option to have some local memory on the motherboard in order to increase performance, feature available on the reviewed motherboard.

On the table below we provide a comparison between AMD 785G, AMD 790GX and AMD 780G. As you can see AMD 785G specs are very similar to AMD 780G, with both having 40 processors running at 500 MHz. The two main differences between the two is the support for DirectX 10.1 on AMD 785G 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 supports HDMI 1.2.

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.

Other chipsets with on-board video from AMD include AMD 690V, AMD 690G, AMD 740G and AMD 780V. AMD 690V, AMD 690G and AMD 740G are based on a DirectX 9 graphics engine, while AMD 780V is 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 Graphics configuration.

SB750 south bridge chip, besides bringing RAID 5 support, has an 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 and allows you to unlock hidden features from the CPU: 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. According to Biostar, TA785GE 128 M also supports ACC, and we guess that this is one of the differences between SB700 and the new SB710.

Hybrid Graphics technology allows the on-board video to work in parallel to a discrete video card under CrossFire mode, 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 Graphics 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 Biostar TA785GE 128 M to ECS A785GM-M, which is based on the same chipset but being a socket AM3 model without the 128 MB on-board video memory, to ECS A790GXM-A (AMD 790GX with 128 MB on-board memory) and to Sapphire PI-AM2RS780G (AMD 780G).

Before going to our tests, let’s take an in-depth look on Biostar TA785GE 128M.