So I haven't used my TV in a few days and turned it on today and turned on my PlayStation4 and when everything was loaded up, all it would do is put out static at the pitch of the load screen and play the background music, but all filled with static. I tried restarting the PS4 along with unplugging all of the HDMI cables and turning the surround sound unit off (its a Yamaha). Nothing seemed to work. I even plugged in the gaming headphones to the controller and they put out static as well.

I'm not sure which is putting out the static-the PS4 or the surround sound unit.

Is there any way to check or figure this out? I read maybe bad grounds, but the whole set up was working fine a few days ago when my brother was visiting and we were gaming. I don't think I bumped any wires in the attic when I was up there this evening. Any ideas or help is greatly appreciated.

Maybe bad connection between PS4 and receiver?

Is the PS4 your only source?

If not, try a different source.  If you don't have a different source, run YPAO on the Yamaha and see if it causes static when it produces the test tones each channel.

Always check/re-seat all your leads (sources, speakers, HDMI, etc.)

The PS4 is the only thing hooked up as my laptop speakers are broken and I have no roommates to plug anything in with.

What I did was unplug the HDMI from the PS4 to the receiver and plugged the HDMI back in to the TV and the audio is just fine. It has to be the receiver it seems. There is no spot for the YPAO on the receiver and I could not find the microphone for it...so I'm not sure what I'm dealing with here.

The model number for the receiver is RX-V665. I'm not so good with these sorts of things and my ex-girlfriend set this up before we split, so I'm kind of a fish out of water so to speak.

The mic plugs into the port on the front labeled "Optimizer Mic".  But you don't need the mic to run YPAO.  In the YPAO setup menu (OSD) there should be something like Test Tones.  I don't currently have either Yamaha receiver setup so I can't tell you exactly which menu/submenu it's under.  It will play a tone or sweep on each active channel that the mic uses for setup.  Im just curious if the channels have static when playing the tones.  

What about selecting the Tuner and playing an FM station.  Does it cause static?  If not, then its the comm between the PS4 and the AVR (HDMI cable, HDMI input, Source settings, etc.)

That AVR only has one HDMI out but it has multiple HDMI inputs.  You could try another HDMI input to see if you have a bad HDMI input.  PS4 HDMI > AVR HDMI IN (1,2,3,4) > AVR HDMI OUT > TV.  Make sure the PS4 Audio settings are correct, also.  (Settings>Audio Output Settings)

The other thing you could try is to switch surround modes.  Change it from Stereo to Dolby to DTS.  Does the static change at all?