Does it? I'm not expert with the viruses...
Formatting C drive is just enough to make your PC clean
Actually that's wrong. If you have a virus on another partition you won't clean it by formatting C:. You have to format the other partition as well.
But, as boyptc said,
But for files, even you reformat many times. There are software that can retrieve data from your hard drive.
Thus, a bad actor could retrieve some of your infected files and if these files are recovered, your PC will be infected again. Some programs (such as Recuva Undelete) can recover deleted files because they are not actually deleted. When you delete a file it is only marked as deleted (and Windows doesn't see it anymore), but at physical level the file is still there. And it will stay there until you will write another file exactly on the place where the deleted file was placed on your HDD.
If you want to make sure that none of the deleted (formatted) data can be recovered, you a need a special software. This software seems to be wiping your HDD but in reality it does more than that: it deletes everything from your HDD and then it fills it with garbage data, then it deletes also this garbage data. As a consequence, your previous files can't be recovered anymore, as after they were deleted, in their place garbage files were written, making impossible to retrieve what was there before the junk files. You can find many such file shredders on the Internet, a very common one being CCleaner.
Regarding reinstalling Windows, it is recommended to fully format your drive at the installation (don't use quick format) and make sure you don't have the network cable plugged in your PC until you finish the installation and you have an antivirus installed. So it's better to have the antivirus kit on an USB stick, then you reinstal your Windows without being connected to Internet; after Windows is installed you install your antivirus and only after you connect your computer to Internet. After that, you should install your drivers (chipset SATA, RAID, etc.) and then install any other program you wish. This is a better approach as while you are installing Windows you don't have an antivirus protection and if your PC is connected to the network / Internet it is vulnerable in this period.