Hey friends. This trick  only works until you reboot your computer. As when system boots up, windows checks the connected hardware and automatically updates the corresponding registry value. So, we had to further investigate.and we have found

the solution that will change the name of processor permanently. Just follow the steps below:

    Open Notepad and paste the following code below:

Windows Registry Editor Version 5.00
"ProcessorNameString"="My Processor name 50000MHz"
(Change My Processor name with your desired value)

    Now save this file as .reg.
    Now create a new shortcut (Right click on desktop>New>Shortcut)

    Now in the location part type regedit / S "Location of the .reg file". For example, enter regedit /S "C:\Processor Name.reg" if your registry file is located in the root of C:\ drive.
    Now copy the shortcut thus made to C:\Documents and Settings\All Users\Start Menu\Programs\Startup (in Windows XP) or to C:\Users\ User-Name\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup (in Windows 7 and Windows Vista). Note: The AppData folder is hidden by default and you will have to enable hidden files and folders from Organize>Folder & Search Options.

It will change the name every time windows boots up.