Lucid Virtu and Intel Quick Sync: Pairing GPUs

Transcoding and Gaming Performance

The reason Virtu is considered such a big deal is simple:  Sandy Bridge's iGPU transcodes video incredibly quickly; the speedup is similar to what we saw when Badaboom debuted. That program proved that leveraging Nvidia's CUDA technology could cut transcode times significantly compared to a standard CPU—without sacrificing image quality.

At present, typical users probably do precious little transcoding, but this could easily change in the not-too-distant future. The proliferation of tablets and media-rich smartphones will give consumers the ability to view content on a variety of devices. Scaling that content to fit both the TV and the iPhone requires transcoding and Sandy Bridge delivers in spades.

At present, only two programs support Intel's Quick Sync technology:  Arcsoft Media Converter 7 and Cyberlink's MediaEspresso 6.5. We opted to focus on MediaEspresso, but have included performance results for the NV GTX 480 when using Badaboom as well. We transcoded a 720P rip of The Incredibles into an iPhone-compatible format and averaged the time-to-encode over three consecutive runs.

Our testbed consisted of an Intel Sandy Bridge 2600K processor (3.4GHz, Intel HD Graphics 3000), an Intel BOXDH55PJ H55 motherboard, 8GB of DDR3-1333 RAM in two 4GB sticks, and a 1TB WD Caviar Black. All tests were run multiple times and averaged. 

We didn't expect to see MediaEspresso outpace Badaboom's CUDA-powered encode times by such a wide margin, but the gap was quite distinct. The 2600K only lags the GTX 480 in Badaboom by a small margin but we expect this is because we're encoding a low-resolution video. The gap between GPU and CPU transcoding performance will always vary depending on the type of encode being done and the various post-processing effects that are applied.

Quick Sync blows everything else away. At just over four minutes to encode a nearly two-hour movie it takes just 63 percent as long as its next-closest competitor, the GTX 480. The presence of the GTX 480 doesn't impact Quick Sync performance at all.

When it comes to Intel's transcode functionality, Lucid has things tightened up and good to go. Things are a bit less certain on the gaming side. We tested two games and both 3DMark's with Virtu enabled; results are below:

3DMark Vantage's performance scarcely twitched with Virtu enabled; there were no signs of visual artifacts or other rendering issues.

Things are much the same in 3DMark 11, although we saw a small drop of about seven percent when we enabled Intel's HD 3000 graphics.We thought we might see problems here since 3DMark 11 uses DirectX 11 while Sandy Bridge's GPU only supports DX 10.1, but nothing of the sort occurred.

Dirt 2 showed a falloff when the GTX 480 was paired with the HD 3000, though not a serious one. The software version we tested was a Release Candidate, not the final version. Issues like this may be entirely resolved by the time Virtu ships out.

The performance difference between the GTX 480 and the GTX 480 with Intel's HD 3000 enabled is well within the margin of error here.

One Significant Annoyance:

The screenshot above (and it's not-shown ATI counterpart) constitute the one thing we dislike about Virtu. While the software is running, there's no way to access NV or ATI control panels—Virtu convinces Windows that it's actually running off the SB GPU. It's unclear if Lucid has a way to eliminate this quirk—the software can be shut off at the task bar, but the display cable must still be shifted back to the discrete GPU.

If you don't mess with the control panel and prefer to define things using in-game controls, there's nothing to worry about here.

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