Virtu d-Mode puts discrete GPUs first, QuickSync second


— 12:48 PM on May 16, 2011

When we took a closer look at Lucid's GPU virtualization tech in our Z68 review last week, we tested Virtu in its default configuration, which requires that the Sandy Bridge IGP be used as the system's primary graphics adapter. This setup aims to let users enjoy Sandy Bridge's QuickSync video transcoding alongside the gaming performance offered proper graphics cards by hiding one's discrete GPU behind Lucid's multi-GPU abstraction layer. There is a catch, however. Because the discrete GPU is virtualized, games and applications can't see it directly. You can also lose out on game-specific optimizations built in the graphics drivers from AMD and Nvidia, whose control panels are inaccessible with the Sandy Bridge IGP serving as the primary display adapter.

As we discovered, this Virtu config fails to deliver on the full potential of one's discrete graphics card. The performance hit only amounts to a few frames per second in some games, but it's considerably larger in others. In Metro 2033, for example, we saw average frame rates drop by 38%. QuickSync transcoding worked like a charm, however.

With an eye toward providing better gaming performance, the most recent versions of Virtu support a new d-Mode configuration that puts the discrete graphics card in the role of primary display adapter. This mode allows driver control panels to load and game-specific optimizations to have their desired effect. The Sandy Bridge IGP is virtualized behind Lucid's abstraction layer and ready for action when video transcoding calls.

Curious to see d-Mode in action, we fired up the configuration and ran a series of gaming tests using the same detail levels and resolutions as in our Z68 review.

As you can see, d-Mode works as advertised. Frame rates were equivalent to what we achieved when running the discrete graphics card on its own.

We didn't experience any issues when gaming in d-Mode, but we weren't finished yet. Next, we fired up MediaEspress to see how d-Mode handled QuickSync. At first, it didn't at all. The app didn't always offer QuickSync acceleration as an option, and it hard-locked the system serveral times as we tried to set up a transcoding job. We also received numerous instances of the same "igfxext Module has stopped working" error message upon loading the app and starting the transcoding process. Eventually, we managed to get the system to complete our transcoding test.

When d-Mode works properly, QuickSync transcoding is nearly as fast as when the Sandy Bridge IGP is the primary display adapter. However, this mode clearly isn't ready for prime time. Even when we were able to get QuickSync to work, the error messages persisted, usually several at a time. Lucid is aware of the issues we encountered and is hoping to resolve them in the next release.

While we had d-Mode up and running, we took a moment to see if the config might work on Gigabyte's Z68X-UD7 motherboard, which lacks display outputs for the Sandy Bridge IGP. Sadly, it did not. The Gigabyte board doesn't give users the option of enabling the IGP, which isn't detected by Windows at all. Virtu can't virtualize what it can't see.

   
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