Driver Avermedia A857 Windows 7 64 — Bits Link

Windows 7 64-bit requires signed drivers. If the installation fails, you may need to disable driver signature enforcement during boot (press F8 during startup).

: Hosts general AVerMedia TV Tuner Drivers for Windows 7 (32/64-bit). System Requirements Driver Avermedia A857 Windows 7 64 Bits LINK

If the driver is installed but Windows Media Center (WMC) doesn't see it: Windows 7 64-bit requires signed drivers