Thanks for your help. I will download it and check the exact specifications.
Meanwhile, i have also checked the settings in my BIOS. it shows same.
Intel Core 2 Duo E7200 2.53 Mhz 2.53 Mhz.
I think it should show 3.66 Mhz. So it is not only a Windows 7 problem.
What may be the issue?