Hi Giogio,
Very carefully check 3 areas in your file structure and remove only the ET5 or EasyTune5 folder if you find them.
First click on All Programs, and if you find an entry for EasyTune5, right click on it to delete it.
Then, go to C:\Program Files\Gigabyte\ and look at the sub folders. If you find a subfolder calledr ET5 or EasyTune5 - delete the folder - no others.
Very carefully: double click Regedit to open your registry. Click on HKCU\Software\Gigabyte\ and look for a subfolder ET5. If you find it, delete it. Don't delete any other folders there, just the ET5. There will be another entry in your registry under your SID, but leave it alone and it will be deleted when the first entry is deleted.
If you are unsure or feel unsafe about editing your registry, have someone who is familiar with registry editing help with that part. When you delete an item in the registry, it is immediate and permanent.
I always export the registry section I am going to edit and save it on the desktop. (that would be the Gigabyte Folder). Then if you delete an entry that was not correct, you can just double click on the desktop icon on the desktop and it will be merged back into the registry exactly as it was before.
Another way to make sure all of ET5 is cleared from your system, it to start Revo Uninstaller, on the tool bar click on "Install Programs" and it will track every step as you install "EasyTune 5". Install the older EasyTune 5, and when finisher, stop Revo Uninstaller. Finally open the "Tracked Programs" in Revo, choose EasyTune 5, and uninstall it. That way it will remove every installed component of EasyTune 5, even ClassId entries placed in the registry.
Try the easier methods listed first.
You should be able to completely get rid of it.