AMD Dual Graphics Performance
When it comes to testing integrated graphics cores and their 3D performance, AMD is ready to produce its trump card – the Dual Graphics technology. Its point is in building asymmetric CrossFireX configuration on the basis of the APU's integrated graphics core, and it really looks like an interesting feature that may boost 3D performance by using entry-level or obsolete graphics cards. It is simple and easy to implement: you just install a discrete Radeon HD series card into your computer, allow the mainboard to initialize both the discrete and integrated GPUs (by checking the appropriate BIOS option), and enable Dual Graphics in the driver.
The symbiosis brings some fruit indeed. The following table shows the 3D performance of a configuration with an A10-6800K APU in three modes: with the APU-integrated graphics core, with a discrete graphics card Radeon HD 6670, and with the integrated and discrete GPUs working simultaneously in Dual Graphics mode.
So we can see that adding a $70 graphics card into our A10-6800K configuration lifts the 3D performance up to a whole new level, allowing to run modern games at Full-HD resolution with medium visual quality settings. The frame rate gets higher by 50% and more in many cases. So the Dual Graphics technology would be perfect if it were not for a few disappointing downsides and limitations that actually negate all of its benefits.
First of all, Dual Graphics can only bring about substantial performance benefits if the discrete graphics card is comparable in 3D performance to the integrated graphics core. The list of recommended models includes AMD's Radeon HD 6450, 6570 and 6670 models, which are all outdated already. The newer Radeon HD 7750 can also be combined with the Richland in Dual Graphics mode but, as our practical testing showed, the graphics driver isn't perfect for such a combination, so there is no performance growth in half of gaming applications.
The second downside we can see about the Dual Graphics technology is that it is only compatible with DirectX 10 and DirectX 11 game engines. Thus, older games may show no performance benefits at all with Dual Graphics configurations. The same goes for certain newer games AMD hasn’t yet optimized its driver for. For example, Dual Graphics doesn’t improve the frame rate in the recently released flight sim War Thunder.
But the most serious problem with Dual Graphics is the image quality you get with an asymmetric CrossFireX configuration built out of an external graphics card and an integrated graphics core. AMD didn’t put much effort into producing smooth visuals. In fact, the Dual Graphics configuration outputs not whole frames but parts of frames as rendered by the integrated or the discrete GPU. These parts are often not in sync with each other, so we can see image tearing as is illustrated by the screenshots below. These are not occasional visual artifacts but a persistent problem which worsens playability greatly.
This image tearing effect can be sometimes observed on ordinary graphics subsystems when the frame rate is not in sync with the monitor's refresh rate. On the Dual Graphics configuration, however, it can be seen even when the VSync option is turned on.
So we wouldn’t recommend you to have high expectations about the Dual Graphics technology. Right now, it is just an experimental feature that allows AMD’s marketing department to draw pretty presentation slides with nice-looking charts. In reality, it is not very useful and not very functional. In fact, it is just glitchy. And we can’t really expect it to improve. The Dual Graphics technology isn’t new. If AMD hasn't bothered to correct its bugs yet, it will hardly do so in the near future.