Microsoft has changed the PC performance rating tool Windows Experience Index for Windows 7 to improve the way it measures faster graphic cards, multi-core processors and hard drives.

The index's top score will go up from 5.9 to 7.9, and add several new tests to more accurately measure the performance of hard-disk and solid-state drives, says a post at the Engineering Windows 7 blog.

Windows Experience Index, first introduced with Windows Vista, is intended to help users discover which parts of their system needs to be upgraded for Windows and applications to run well, or if the PC needs to be replaced.

Reviews of the first public beta of Windows 7 indicate that it generally runs faster and more smoothly than Vista, despite the two sharing a very similar codebase.

Windows 7 review

Windows 7 forum

But critics have already begun questioning the revamped index's usefulness and accuracy. One beta tester, called 'Hurricane Andrew' on Microsoft's MSDN developer website, complained that an older hard drive using the slower IDE interface was awarded a much higher rating than his newer, larger hard drive using the faster SATA-II interface. "I hardly believe that's accurate," he wrote.

Others complained that the new scale, from 1.0 to 7.9, was counterintuitive, or that the criteria for drive performance should not have changed between Vista and Windows 7 for consistency's sake.

Michael Cherry, an analyst with the independent firm Directions on Microsoft, said he "doesn't put much stock" in the index's scores.

A Microsoft representative said that the company was "closely monitoring" input from beta testers about Windows 7, including for the new index, but would not say if changes would result from the feedback.

Windows 7 Experience Index

Windows 7 apps may not run faster on quad-cores

The Windows Experience Index, found under the System Icon in Vista or Windows 7's Control Panel, quickly scans hardware before delivering five results, including for: processor, memory (RAM), graphics for general desktop work, gaming graphics performance, and the primary hard drive's performance. The results are based on the rated specifications of each component, not on their actual performance history in the scanned PC.

Because PC performance is often determined by the speed of the slowest-performing component, the index's 'base score' is defined by the lowest of the five scores, rather than an average of all five.

PCs with a base score of between 1.0 and 2.9 can run Office applications and surf the web, but not play games and videos or use Vista and Windows 7's Aero graphical user interface, Microsoft says.

Computers with a base score in the 3.0-range should be able to run Aero and most of Vista and Windows 7's new features, while those with scores in the 4.0 to 5.0-range should be able to enjoy high-definition (HD) video and 3D gaming.

An analysis by the Malaysian technology blog TechARP found that dual-core CPUs that were scored a maximum 5.9 in Vista's Windows Experience Index will now be scored between 6.0 and 6.5.

"Well-performing" triple-core CPUs, which were not available during Vista's release, will be scored between 6.3 and 6.9, while quad-core CPUs will score somewhere above 7.0, TechARP said.

Microsoft is setting 7.9 as the performance benchmark for an 8-core CPU with simultaneous multi-threading (SMT). Eight-core CPUs, such as future versions of Intel's Nehalem chips , aren't even available for PCs yet.

TechARP said that Windows 7 PCs sporting triple and quad-core CPUs will excel at multi-core enabled applications such as very large Excel spreadsheets, sophisticated graphics rendering, software compiling and scientific applications.

However, it said such apps remain in the definite minority today, meaning that most software won't feel any zippier to users when run on higher-scoring 3- to 4-core systems.

In another change, Windows 7's Experience Index will not only measure how fast disk drives are at reading data, but how fast they are at writing large and small blocks of data. This will be especially helpful for measuring the true performance of solid-state disks (SSD) , which currently read data much more quickly than they write it.

On memory, Windows 7 will continue to base the score primarily on the RAM's speed, while limiting the score for lower amounts of RAM. PCs will need more than 3 GB of memory to gain scores greater than 5.5.

To gain a gaming graphics score in the 6.0- to 6.9-range, PCs need to support Direct X 10 graphics and deliver between 40 and 50 frames per second of gaming or video at 1280x1024 resolutions, says Microsoft'sEngineering 7blog.

No news on Windows 7 Upgrade Advisor

The Windows Experience Index is different from the Windows Vista Upgrade Advisor , a free application that is downloadable from Microsoft's site. With it, users can determine which version of Vista their Windows XP PCs can support, and whether components or software need to be upgraded.

Microsoft would not say exacty if it will release a Windows 7 Upgrade Advisor. A representative said: "Microsoft is investing in tools like the Windows Upgrade Advisor to help customers assess application compatibility. However, we have no additional information to share at this time."

Customers eager to find out today if their current PC is Windows 7-capable can use the Vista Upgrade Advisor, as "Windows 7 is being designed to run as well as or better than Windows Vista," she said. "As a result, there aren't new requirements that machines must meet in order to run Windows 7 well and deliver a truly great experience."

Consumers interested in finding out the Windows Experience Index score of various PC models and components can consult sites such as for laptops or for video cards and CPUs. They can also upload their index score to

Computerworld US