Though long in substance above, I did do what you had asked with the tv and same pretty much graphics card/audio soooooooo..... if all equipment it working right, what I wrote will work, and PC speakers, really? Run the 2 spdif optical wires, one from the tv, the other from the Computers mobo or other sound card, and just call it a day. Unless if you really plan on replacing this with pc speakers, I hope they are some Logitech Z5500 THX stuff there really isnt much other to sound better then even a cheap amp and ur own speakers, but even still there, you are analog or Spdif Optical only with the z5500 as well, so just use ur speakers, ur amp, and stop wasting the time trying to get the 6800XT sound working till you get a better amp that can support the card or other sound cards better
. Your only 5.1 (assuming ur using the yamaha to do more then just 2.0 stereo), with a cheap amp, not many sound settings anyways with it, for what is the goal? If you think that going to your receiver, then to your tv is the smart choice and right way, days of old hooking up is really gone, and ur tv has features ur pc/console will that going to say a new 4K amp, that still may support 4k60 with hdr but its having dolby vision ready av receiver is going to cost a good penny, so then really, go buy 2 optical cables, plug them in, call it a night, you are not missing anything at all between that amp and SPDIF sound vs HDMI at this point, or what you are thinking that 6800XT sound is going to give you and be different???
EDITED:
OK:
6800XT out HDMI, to TV, NOT receiver, to input HDMI 2.
Switch tv input setting for HDMI 2 to HDMI 2.0 format to Enhanced if it says it is on 2.0 Enhanced some receivers do not like HDMI 2.0, so switch that to Standard
Take a HDMI cable from INPUT 1 (arc, MUST SAY ARC) of tv, to OUTPUT ARC of Receiver.
A: Audio
R: Return
C: Channel
Right click on speaker Icon lower right on ur pc (providing you have a ACTUAL AMD driver installed for your 6800XT not widows basic) Select Input settings/Select AMD-Hisense (selecting this one should get you sound coming from your pc to then the tv speakers) Then there "may" be a setting saying AMD-Yamaha Digital, which would be awesome for then your pc is seeing arc hooked between your tv and the Yamaha, and if not continue 2 down.
If Yamaha is there:
Select it and set to default. Configure now selectable on the lower left and set up ur speakers for output 2.0/2.1/4/5/7.1 should you see it pop up as AMD-Yamaha Digital or Digital Yamaha, in any case, if not seeing your Yamaha keep reading below. If it does show your Yamaha at this point Set it up also for small or large speakers, click done. Go to properties in the same window lower right, and change the sound advanced setting to 24/48 as a baseline, almost ALL receivers unless really old should do that setting no problem.
Now with receiver on, may have to hit tv audio button if your receiver has one, my Marantz does, and you should now have sound, and ANYTHING hooked to that tv in the other ports for sound, analog and HDMI, will ARC to the Receiver, and the other way around, for anything lesser then like 360 NOT USING hdmi OR A wii (NOT u) can be then hooked to the yamaha, and its video will then be seen on Video HDMI Input 1 of the tv.
Since as you mentioned that Yamaha receiver does 1080P not 4K, then you are doing the "reverse" and using your tv as the "4K Switch" and video, and the Yamaha and The Hisense ONLY to talk back and forth to do the Audio coming from the 6800XT you plugged into the tv, and consoles like PS XB that are 4K going to the tv, and now ANY of the smart features the tv has, will also be sent to the Yamaha in AUDIO FOR ONLY through arc so you can have 4K picture, and STILL 5.1 on a older unit like you have.
If you still have no sound go and see if you need to manually switch tv, in tv sound setting from tv sound to ARC if it will let you. Also, depending on grade of HDMI cable will give you audio drops, and in some case may need to play around with the Auto/Passthrough/Dolby/Atmos/DTS settings within the tv to see what your receiver likes coming from the 6800xt to play nice sometimes with older arc supported receivers. But at this point you should have sound, I know, because I finally got my set up finished just now in my man cave with My Hisense put back up in front of my with my marantz and haw I have my Xb One X and my 6700XT hooked up to my tv and my Marantz sound, even though my Marantz Does 4K input on the HDMI line, I prefer to hook this stuff up this way anyhow for I have a TON of crap, more inputs then the marantz has anyway, and it does not do Dolby Vision when our tv does, and the XbOne Has Dolby Vision so only way to get that to work, and HDR off the PC to work correctly, is direct to the tv, and ACR to the Marantz/Your Yamaha so I can still have Uncompressed 7.1 surround sound, and make use on Dolby Vision and Games/Movies/Streaming services I play off my XbOne that supports it then for best in Sound and Video.
But anyone reading this you do not need a 4K receiver, and if all you care about, and if all you want is 5.1 surround with a sub for PC/Console Gaming with a 4K ready tv, then all you really need then is do above, plug all things to the tv, and run a Spdif cable (one single cable) from the tv with or without arc to a receiver with or with out arc, and just run the (red light) spdif in the back of your tv, to the back of even the oldest of receivers just as long as it supports spdif and dd or dts and call it a day
. You are not sending ANY video at all over Spdif or even Arc for that matter if it goes all to your tv first using one of the 2 methods above to achieve sound from ur tv, smart, pc, or console. And in most cases, any good older receiver for that matter will have at least 2 "optical" inputs (or more), one for your tv, and another for this problem this guy is having and run the Spdif "optical" then from your computers mobo or sound card, call it a day
And if thats not enough they make switches you can buy at amazon to plug the hdmi line into with a hdmi out, that can even strip the spdif signal without even using a tv if need be.
Such as this (one of many I own of different other types) Click me! That one has the most universal settings of any of the other switches I own, and the most expensive because of it, for it has 4 HDMI in 4K60 with TWO HDMI outputs that you can run to different sources or at the same time 2 other parts of the house and it strips the basic 5.1 Spdif from both output signals to boot.
This is how I get sound going from my Hisense H8G from my PC's 6700XT and my XbOne and my Hisense Smart Crap like hulu/Netflix/Vudu so it will then send the sound to my receiver be it with my Now Marantz (4K60), or the Denon (1080P) HDMI units I had hooked up before that, which before that I had ones with NO hdmi at all, and gone all Analog, and do not get me started on that for if I want as pure as I can make it then its a Creative X3 and nothing but all analog to my Marantz or anything else before all the the rest, for digital is good for coming off the tv, doing uncompressed digital from consoles or smart tv when hooked like I mentioned, but really from a game, movie, audio stand point for ME, I prefer all else from my pc be almost all Analog audio, sounds better to me IMHO. So you asked if anyone can tell you how to get sound working with your 6800XT and besides me having a 6700XT everything I just wrote out again will get you sound UNLESS ur receiver is craped out, but then just do the spdif out the tv to your Yamaha and still call it a day. Ur yamaha only does 5.1 anyways so HDMI 4K Arc no arc, just put ur pc and consoles to your tv, run the one Spdif optical cable and quits at that point. Your receiver has 2 opticals in, so run a optical off ur sound card or mobo sound card and forget HDMI all together, and run another Optical to your 2nd from your tv, so all the smart crap and consoles will have sound at ur receiver, and not even touch then a single in or out hdmi going to or from your Yamaha, just the 2 optical wires from pc and tv, and speaker wires call it done for digital ur trying to get from ur 6800xt then through its HDMI and Software is really no different sounding or better then them 2 optical wires in its place, your receiver if HDMI and ARC worked, your 6800XT cannot send anything better to a Yamaha that
PCM tends to be the easiest method, if a device fails to support PCM, its pretty much broken. Bitstreaming and HDMI does have its cons. I don't like a video feed for audio only myself.
I agree for though a PITA, big time, I have stuff 2.0 analog, 7.1 analog, Spdif, and HDMI for depending on what I am doing or watching, and what on and with, so for me, imho, I will agree for I really only use the HDMI for sound, not for games or youtubes, but for movies I have on BR that are atmos or anything the like over DTD HD quality, all the rest is old games, spdif if older then a XbOne and no HDMI out, and all the rest is direct analog right from my X3 for all else like music and games sound better to me, IMHO, then anything compressed. Between my amp and Pot Player (yes thats real and again IMO is far better then VLC for it has sooooooo many adjustments and play toys over VLC (though I still use it too), but for movies and sound and changing how Id like to to sound, can miniplate the sound to my taste between pot player, my pc/Amp using just Analog, and I will argue till I day that if you see NO options in ur game(s) that allow you to change between 5/7.1 surround sound and just says you can adjust sound levels for mic speaker and the like, that UNLESS you play that game in Analog, off a PC not console, youre getting compressed "simulated" surround not as intended as you would if you ran just pure analog from ur PC to a 5/7.1 analog IN, not out, capable receiver. All good if your using a console, but gaming/music/and movie playing of ur PC is very different and can be a Major PITA.
And for those that want to argue with me HDMI/Optical is MUCH better, then let me ask you this:
If analog is soooooo dead and HDMI, and Optical (though very very old technology) why do board, and card manufactures still really put them in, with bad butt DAC inside (or software) when they could just save that money? Or better yet, why are there sound cards you can buy that have Analog with just 2.0, so you can run a really good external dac, and bad butt speakers, if they, and people like us still see a need for it, costing a TON more money then my X3 (and I am sure in 2.0 stereo sound fantastic vs my X3), if one was to say HDMI (compressed, uncompressed from ur pc with those options mentioned above in game sound settings menu can send then true 5/7.1 provided you have the right amp and hooked up correctly) or SPDIF for even the modest of sound cards built into mobos today say what bit rate and HRZ that crappy Realtek can do in optical, example(s):
For digital audio, if an HDMI device has audio, it is required to implement the baseline format: stereo (uncompressed) PCM. Other formats are optional, with HDMI allowing up to 8 channels of uncompressed audio at sample sizes of 16 bits, 20 bits, or 24 bits, with sample rates of 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, or 192 kHz.
[5]: §7 HDMI also carries any
IEC 61937-compliant compressed audio stream, such as
Dolby Digital and
DTS, and up to 8 channels of one-bit
DSD audio (used on
Super Audio CDs) at rates up to four times that of Super Audio CD.
[5]: §7 With version 1.3, HDMI allows lossless compressed audio streams
Dolby TrueHD and
DTS-HD Master Audio.
[5]: §7 As with the Y′CBCR video, audio capability is optional. Audio return channel (ARC) is a feature introduced in the HDMI 1.4 standard.
[41] "Return" refers to the case where the audio comes from the TV and can be sent "upstream" to the AV receiver using the HDMI cable connected to the AV receiver.
[41] An example given on the HDMI website is that a TV that directly receives a terrestrial/satellite broadcast, or has a video source built in, sends the audio "upstream" to the AV receiver.
[41]
For digital audio, if an HDMI device has audio, it is required to implement the baseline format: stereo (uncompressed) PCM. Other formats are optional, with HDMI allowing up to 8 channels of uncompressed audio at sample sizes of 16 bits, 20 bits, or 24 bits, with sample rates of 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, or 192 kHz.
[5]: §7 HDMI also carries any
IEC 61937-compliant compressed audio stream, such as
Dolby Digital and
DTS, and up to 8 channels of one-bit
DSD audio (used on
Super Audio CDs) at rates up to four times that of Super Audio CD.
[5]: §7 With version 1.3, HDMI allows lossless compressed audio streams
Dolby TrueHD and
DTS-HD Master Audio.
[5]: §7 As with the Y′CBCR video, audio capability is optional. Audio return channel (ARC) is a feature introduced in the HDMI 1.4 standard.
[41] "Return" refers to the case where the audio comes from the TV and can be sent "upstream" to the AV receiver using the HDMI cable connected to the AV receiver.
[41] An example given on the HDMI website is that a TV that directly receives a terrestrial/satellite broadcast, or has a video source built in, sends the audio "upstream" to the AV receiver.
[41]
Taken from here (click me)
And for Spdif:
S/PDIF is based on the
AES3 interconnect
standard.
[3] S/PDIF can carry two channels of uncompressed
PCM audio or
compressed 5.1/7.1
surround sound (such as
DTS audio codec); it cannot support lossless surround formats that require greater bandwidth.
[4]
Taken from here
And this site here breaks it down even further, and what games that are out there that do true 5/7.s PC surround sound going from ur Spdif optical, or HDMI (click me) other then that, to get true PC GAMES to play in TRUE surround sound it must be either Analog or Game supports sending the codec UNCOMPRESSED through HDMI. For consoles this is no big deal at all, but a PC, its a PITA to get just "one cable to rule them all" for ALL have pros and cons, I am just trying to metion, if ur going to use even a cheap receiver, or a high dollar one, make sure it has ANALOG IN, not OUT in the back of it, and run a Optical, and the analog and then call that a day, if in the end run all you want it basic better then tv sound, for it can really take off down the rabbit hole very quickly when you find out what all this crap can really do if you take the time, and hook it all up right for YOUR situation(s)
Another Quality book written, and un edited by, funboy