~5% more so far in Win 8 vs. Win 7 and it may be even better when Win 8 is actually released.
http://www.pcstats.com/articleview.cfm?articleID=2622

Windows 8 Scheduler to More Efficiently Work with Multi-Core Chips
[10/14/2011 10:36 AM]Advanced Micro Devices hopes that Microsoft Corp.'s next-generation Windows 8 operating system will work with multi-core central processing units (CPUs) more efficiently than Windows 7. As a result, the company's FX-series chips with up to eight cores will show higher performance than today. A big question is how AMD FX will show itself in comparison with Intel's chips.

According to a slide that AMD recently spread, the new chips show up to 10% performance advantage in Windows 8 compared to existing performance in Windows 7. The performance boost is observable in non-demanding video games and can be less noticeable in other applications as well as game titles that heavily rely on performance of central processing units. The chip giant attributes the advantage to the new scheduler of the next-gen operating system, which more efficiently manages microprocessors with numerous cores.
Based on independent tests by X-bit labs, the FX chips fail to become an enthusiasts' choice as the top-of-the-range eight-core FX-8150 model can barely beat Intel's mainstream quad-core Core i5-2500 processor that even lacks the company's well-known Hyper-Threading technology.
While AMD demonstrates the advantages of its own eight-core microprocessor in the Windows 8 environment, but does not indicate whether other CPUs also benefit from the next-gen OS. It is widely believed that Microsoft's operating system due next year needs less compute resources than existing OS and will therefore work better on all systems.
Tags: AMD, Windows, Bulldozer, 32nm, Orochi, Zambezi
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