Welcome to WinDrivers, JulienCh! Since Via doesn't provide a Win8 driver for your Envy, yet. You may be out of luck. You could try installing the Win7 driver from Via, but my reading of Via's site suggests this won't work. Still, it's worth a shot if you haven't tried it already. You might also try going to Device Manager, finding your non-functional device and using the Update Driver feature to search the Internet. It's possible that Microsoft has written a driver for your Envy.