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GPU virtualization and QuickSync support
The Z68's FDI link and display controller give the chipset all it needs to exploit Sandy Bridge's integrated HD Graphics component. That's great if you're going to be using the IGP as your primary graphics device, but it won't allow QuickSync to coexist peacefully with a discrete graphics card. To combine the two, you'll need Lucid's Virtu GPU virtualization software, which Asus, Gigabyte, and MSI are all bundling with their Z68 motherboards.

Lucid, as you might recall, is responsible for the vendor-agnostic Hydra GPU teaming scheme that's been kicking around for a couple of years now. Hydra is designed to masquerade as a graphics device and intercept API calls, which are then balanced across multiple GPUs to improve performance. Virtu uses a similar multi-GPU abstraction layer. Rather than load-balancing, it sends API calls associated with games to a system's discrete graphics card. Everything else runs through the Sandy Bridge IGP, which serves as the primary display adapter and allows the discrete GPU to slip into its idle mode when not in use.


Virtu laid out. Source: Lucid

The Intel IGP has to be the primary display adapter for QuickSync to work, so you'll always need at least one display hooked up to the motherboard. Virtu allows additional monitors to be fed by a discrete graphics card, though. When you're playing games, the contents of the discrete GPU's frame buffer are copied over to the IGP's frame buffer in much the same manner as Nvidia's Optimus switchable graphics technology for notebooks.

Because Virtu hides the discrete GPU behind an abstraction layer, the vendor control panels associated with AMD and Nvidia graphics cards aren't accessible. You'll still have to install the drivers for your discrete graphics card, but an error message will pop up every time Windows loads warning that the control panel doesn't recognize the primary display adapter. The discrete GPU is hidden behind Virtu, which uses it as a rendering engine for a software layer that knows nothing of application-specific optimizations in the latest Catalyst or ForceWare drivers. Applications with optimizations of their own won't be able to see your discrete GPU, either. Some additional performance may be lost due to overhead associated with Lucid's abstraction layer.

The good news is that the Virtu experience is a pretty seamless one. A Lucid app sits unobtrusively in the system tray and allows users tweak a few settings. The ability to briefly display a Virtu icon when the discrete GPU kicks into gear is a nice touch, and the performance optimization slider is a must. We experienced several crashes with the slider set to anything but maximum quality, which was perfectly stable.

Virtu already has built-in support for a huge number of games, and adding new ones is trivial. Don't expect to be able to use any old graphics card, though. Virtu support is limited to the Radeon HD 4000, 5000, and 6000 series from AMD and the GeForce 200, 400, and 500 series from Nvidia.

To find out how well Lucid's GPU virtualization tech works, we first tested QuickSync with CyberLink MediaEspresso 6.5. We used the app to transcode 65 minutes of 720p HD MPEG2 video to H.264 at a resolution of 320x240. The test was run on a Core i5-2500K system with its IGP disabled and a Radeon HD 5870 discrete graphics card installed. Our QuickSync config had the IGP enabled and Virtu installed, still with the Radeon in tow.

As you can see, QuickSync cut our encoding time nearly in half. No wonder folks were choked to learn that the P67 wouldn't be able to make use of this functionality. To be fair, MediaEspresso isn't exactly known for well-optimized encoding routines that run entirely on the CPU. Our results nicely illustrate that QuickSync is indeed working properly alongside a discrete graphics card, though.

Curious to see what sort of performance impact Virtu might have on games, we fired up a collection of recent titles and tested the Radeon running on its own and behind Lucid's abstraction layer. All the games were run at 1080p with high detail levels and doses of antialiasing and anisotropic filtering. I didn't notice any obvious differences in visual quality between the setups while testing, but I was also bleary-eyed from all too many hours of consecutive benching.

Virtu has a minimal impact on performance in some tests. However, there's a notable frame-rate hit in Bulletstorm, Civilization V's leader benchmark, and especially Metro 2033. Frame rates in Metro 2033 drop by nearly 40% when Virtu is enabled, highlighting the perils of virtualizing one's GPU.

What about Virtu's ability to lower system power consumption by putting discrete graphics cards into an idle mode when they're not in use?

According to our power meter, Virtu does save a few watts when idling on the Windows 7 desktop. We see the same gap in power consumption with a Bulletstorm load, suggesting that the difference has nothing to do with idling the discrete graphics card. I'd hazard a guess, but it's only three watts, and we have more interesting things to discuss.