I do not feel that exists any shady trick on it If it turns to be the LinkBoost feature. Newer cards starting from 7900 GTX have the feature added in it. It boosts 25%. Not sure but I think only Nvidia motherboards have this feature added on bios.

Quote Originally Posted by AnandTech

LinkBoost

One of the features unique to the nForce 590SLI and 680i SLI MCP is a system called LinkBoost. If a GeForce 7900 GTX or GeForce 8800 is detected on either MCP then LinkBoost will automatically increase the PCI Express and MCP HyperTransport (HT) bus speeds by 25%. This increases the bandwidth available to each PCI Express and HT bus link from 8GB/s to 10GB/s.

Since this technology increases the clock speed of the PCI Express bus by 25% to the x16 PCI Express graphics slots, NVIDIA requires certification of the video card for this program to work automatically. In this case, the 7900GTX and 8800 series are the only compatible cards offered, although you can manually set the bus speeds and achieve the same results depending upon your components. We feel this feature is worthwhile for those users who do not want to tune their BIOS and go through extensive test routines to find the best possible combination of settings.


In essence, NVIDIA is guaranteeing their chipset's PCI Express and HT interconnect links are qualified to perform up to 125% of their default speeds without issue. While LinkBoost is an interesting idea, the 25% increase in PCI Express x16 slots and HT bus speeds yielded virtually the same performance as our system without LinkBoost enabled in most cases.

Its actual implementation did not change our test scores in single video card testing but did provide a 1%~2% difference in SLI testing at resolutions under 1600x1200 in several game titles. The reason for the minimal increases at best is that the performance boost is being applied in areas that have minimal impact on system performance as the link to the CPU/Memory subsystem is left at stock speed thus negating the true benefits of this technology.
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So probably some people have this feature enabled or might be probable that drivers enable this when it is being installed after a hard restart.

I think it should show the exactly clocks even after the clocks had been upped by the Linkboost feature. Well some softwares do not work correctly anyway.

Metroid.