30 FPS with a GTX 1080? Seems like your PC started your graphics card severely underclocked. If it happens, you have to restart your computer until it's running at the normal speeds. I believe it has something to do with the Windows 10 Anniversary Update a while back, and it's a problem that still persists.

Get a new HD cable the signal is too week

Try windex

does this happen when in a game or does it persist even when the game is closed? if only in game then you GC might be crapping out.