With Windows 8 build 7850 leak, Modern task Manager was revealed as well. Now we have found that it was still unlocked in Windows 8 build 7850 and MDL forums user NaiveUser shared a registry hack to enable Modern Task Manager in Windows 8.
To unlock Windows 8 Modern Task Manager, following Registry hack should be done :
Go to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Curr entVersion\TaskUI
Create a 32bit value “TaskUIEnabled”, set its value to “1″
Update: We have created a tool, which would help you to unlock this and other features with a click. You can download the tool from here.