How i can clean and remove viruses from my PC?

I'm using window 8.1 64 bit. I'M suffering from a unremovable virus name "system vollium". I'M unable to remove it through any antivirus. When I attach any USB to my PC, it also effect that flash. Now told me, how I can remove this virus permanently and which antivirus should I use to escape from internal and external viruses. This virus came into my PC through USB.