I also have a 8000 Series 8 Samsung. Suggest you assure that the PC to TV HDMI cable is routed to either the #3 Or #4 HDMI ports on the TV. These will be the top two. The source button on the remote should tell you if your properly connected.
You probable have already done the above, but I hope its this simple.
Note: I have a sound bar hooked into the #2 ARC port.