CrossFire and SLI Performance Fix for Vista, Part Deux

Posted 12/05/2007 at 9:13am | by Mark Soper

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Back in July, Microsoft rolled out a fix for a nasty bug in its Windows Vista SLI and CrossFire multi-GPU support: Windows Vista was using only one of the GPUs! However, the Inquirer.net website reported yesterday that a more subtle bug is still plaguing some multi-GPU setups: a problem with load-balancing between GPUs.

Load-Balancing Woes and System Slowdowns

If one of the GPUs in your system is very busy, and and other idle GPUs receive a new DMA packet, you may experience scheduling latency. In plain language, your system slows down until all GPUs are assigned work to do. If you like to juggle games and other applications at the same time on your SLI or CrossFire system, you're a prime candidate for this type of slowdown.

Meet LDA, a Way to Avoid Saying "SLI" or "CrossFire"

This update isn't going to show up in Windows Update, at least not for awhile. And, if you ran into it during a casual scan of recent downloads, you might not even recognize it. That's because Microsoft is now referring to multi-GPU configurations as Linked Display Adapter (LDA) setups. SLI and CrossFire fans, make a note of this: every time you see a reference to LDA at Microsoft, think SLI (nVIDIA) or CrossFire (ATI/AMD).

Learning More About the Update...and Getting It

Microsoft has information about the hotfix, available for both 32-bit and 64-bit Windows Vista, at Knowledge Base article 945149. You must request the hotfix from Microsoft, rather than download it directly from the KB article. Microsoft promises a download link within 8 business hours, as we discussed in our article Hotfixes by Email - Just What the Windows Doctor Ordered.

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