Dual Graphics: Hybrid Crossfire Done Right?
Dual Graphics: Hybrid Crossfire Done Right?
Some of you may remember two competing technologies that were originally introduced years ago: Hybrid SLI and Hybrid Crossfire. Their goal was to have the system’s integrated graphics processor and a discrete GPU work in tandem to increase in-game performance over what an IGP alone could provide. Unfortunately, the AMD / ATI solution didn’t work all that well due to the somewhat obsolete IGPs being used while Hybrid SLI never really caught on outside of the notebook market. NVIDIA has since gone on to implement Optimus –an evolution of the original Hybrid SLI concept- on Sandy Bridge platforms while AMD has now finally introduced their own similar technology called Radeon Dual Graphics.
Much like NVIDIA’s technology, Dual Graphics only works under the Windows 7 OS and is able dynamically apply GPU acceleration when it’s needed. However what it does that technologies like Optimus (and the desktop version Synergy) and Virtu can’t is leverage the rendering power of both the IGP and dGPU for increased performance. In layman’s terms, AMD’s drivers now allow for mixed Crossfire configurations between certain discrete GPUs and the graphics coprocessor in A8, A6 and A4 series APUs. The APU acts as the primary display output source while the discrete GPU sends its signals through the onboard PCI-E interface and onto the dedicated I/O pathways.
This may sound simple and straightforward but there is a somewhat complicated set of compatibility requirements that need to be addressed before Radeon Dual Graphics will work with A-series APUs. In short, the graphics controllers on the A8 (HD 6550D IGP) and A6-series (HD 6530D IGP) processors are compatible with any AMD graphics card based off of the Turks and Caicos cores (HD 6670, HD 6570 and HD 6450) while the HD 6410D IGP in the A4 branded APUs will only work with the HD 6450 and HD 6350 cards. The E2 series APUs aren’t compatible with Dual Graphics due to their entry level market positioning.
Once AMD’s Vision Engine Control Center picks up a Radeon Dual Graphics compatible system along with a supported discrete GPU, it will then assign the Crossfire grouping a new name. For example, combining a HD 6670 with the A8 APU will result in the system displaying HD 6690D2 as the primary display controller once Crossfire is enabled. The chart above illustrates this for other IGP / dGPU combinations as well.
Alongside the potential performance benefits of this technology, multi monitor outputs can also be augmented. With the APU’s ability to feed two monitors at once and AMD’s 6000-series discrete GPUs able to output three display signals, up to FIVE monitors are supported with Radeon Dual Graphics.
Naturally, with all of this signal routing and GPU switching taking place, there are a million and one things that can go wrong somewhere along the line. So we decided to test just how well Dual Graphics works in the real world….
First up we have 3DMark11 and indeed it looks like the APU and discrete GPU are able to work in tandem for a cumulative performance increase. Considering the Dual Graphics configuration was deceptively simple to set up, this first result bodes well for the technology’s future.
In a real world gameplay scenario, the results of this technology are impressive to say the least. At 1920 x 1080 the combination is able to more than double the performance of the APU by itself while adding about 40% to the framerates achieved by the HD 6570. It seems like Dual Graphics works quite well since there’s a massive increase over the rudimentary performance granted by the APU itself.
Unfortunately, in F1 2010 we see the other side of the coin since compatibility with this title is less than stellar. At 720P the Dual Graphics setup struggles to beat the IGP’s number while being trounced by the HD 6570 on its own. Things go a bit better at a higher resolution but the framerate increase isn’t anywhere close to the results in Just Cause 2.
When it works, Radeon Dual Graphics works well but its fluid integration lives and dies by the driver stack’s game compatibility. There are obviously some teething pains which boil down to driver issues rather than a fundamental problem with Dual Graphics but that really shouldn’t lead you away from a Dual Graphics solution. We’re told that AMD’s is still working out some kinks but to be honest with you, we were left with a very positive first impression of this new technology regardless of the hiccup within F1 2010 and some uneven load balancing (as seen in the image above). Plus, with AMD’s new Crossfire app profiles being rolled out with some regularity, any problems should be easily overcome with a few simple downloadable tweaks.
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