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You won’t guess it from the model code but the Foxconn A7DA-S uses the new AMD 790GX chipset. This is an interesting piece of silicon that you can think of as a 790X chipset with the addition of the Radeon HD3200 graphics core from the 780G. Adding a relatively feeble graphics core to a chipset that is capable of CrossFire may sound like a strange idea, but there is method to AMD’s apparent madness as the 790GX effectively offers you two motherboards in one.
If you’re building yourself a Media Centre, office machine or a relatively basic home PC then you can use the integrated graphics without the need to splash out on a dedicated graphics card. Indeed, though specification of the Radeon HD 3300 graphics core appears identical to the HD 3200 core in the 780G chipset as it has 40 Unified Shaders, a 32-bit memory controller, supports DX 10.0 and runs at 500MHz, AMD claims that HD 3300 offers up to 30 percent more performance than HD 3200. How can this be?
In this case the answer lies in the graphics memory. 780G/HD 3200 uses shared system memory that GPU-Z reports as running at 500MHz with bandwidth of 4.0GB/sec. By contrast HD 3300 memory runs at 700MHz with bandwidth of 5.6GB/sec, but as we understand it that isn’t entirely true. 790GX adds a feature called SidePort, which is on-board memory for the graphics. In the case of the Foxconn A7DA-S (the S suffix stands for SidePort) it’s 128MB of DDR3, however early samples of the Biostar TA790GX A2+ have 64MB of DDR3. If you buy the basic Foxconn A7DA you don’t get SidePort, but as things stand that doesn’t matter as the current crop of ATi drivers don’t support SidePort and in our testing 790GX had exactly the same performance as 780G.
That’s something of a let-down, but we were encouraged when we plugged in an HD 3450 graphics card to test the Hybrid CrossFire feature and found it was enabled by default. Previously you had to install the graphics card and then enable CrossFire but with 790GX it’s a one-step operation. At present you can only use an HD 3400 series graphics card in Hybrid CrossFire as per 780G, but you have to assume RV710 and 730 will also be included once they have been launched.
Other features of 780G are carried over to the 790GX so you get ATi’s superb video decoder, a choice of display outputs – on the Foxconn there are VGA, DVI and HDMI – and you can install any AMD dual, triple or quad core desktop processor.
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