Onkyo TX-NR7100 problems with displaying PC

[digitalmallrat]

Hello all! New to the forums here although I've lurked for some time. I appreciate all the vast expertise you guys have!

So here's the deal. I recently purchased an Onkyo TX-NR7100 to use with my PC for 4k/120hz/HDR gaming on my LG C1. I specifically chose this model because I was lead to believe it is a true 2.1 HDMI / 40 gbps. I've read that with older (and even newer) AVRs, people have had to separate audio and video with two cables to be able to get 4k/120hz/HDR gaming. This seemed to carry other issues (some users having to run two displays, input lag, etc), and I wanted to avoid this so I went for an AVR that supposedly would only need one HDMI from PC to AVR and another HDMI from AVR to TV. However, I've been encountering some weird and frustrating bugs that I can't seem to resolve.

Backstory and setup: When I got the receiver set up, I put the LG C1 on HDMI 2 (eARC) and connected it to the 8K Main HDMI port on the Onkyo. I have the LG C1 set to PC mode for HDMI 2. I then have HDMI input 5 (PC) on the Onkyo connected to my PC (RTX 3080 Ti). I set the HDMI signal settings on the Onkyo to 8k Enhanced. I boot the PC and I see the boot screen starting, then the Windows logo appears, but then suddenly the screen goes blank right before I would enter my login credentials. I check the input on my TV and it says "No Signal" for HDMI 2. Nothing I can do can get Windows to display.

What I tried: First thing I did was check my PC was functioning okay by connecting it directly to the TV and there's no problems. I get 4k/120hz/HDR/gsync content. I then tried swapping my PC from HDMI input to input on the Onkyo but all of the other ports did the same thing. I then tried using other HDMI 2.1 cables I have (3.3ft and 6 ft) with no luck (I have around 4 of these cables). I also tried using HDMI 1 on my TV (which doesn't have eARC). I read some people having success by powering the units off, unplugging the HDMI cables, waiting 10 minutes, and then plugging them back in after rebooting but I had no success here either.

What finally worked: After fooling around with the Onkyo settings for some time (and hard resetting it a number of times), I plugged the PC into HDMI 1 (which is BD/DVD) and changed the Onkyo's settings to swap HDMI input 1 from BD/DVD to PC -- and it works. 4k, 120hz, and HDR all work. Unfortunately, I can't get Nvidia's Gsync to work through the Nvidia Control Panel, although it does work when I have my PC plugged directly into the TV. However, I believe I can get Gsync to work if I do the workaround I mentioned earlier in this thread of separating video and audio (if I run an HDMI from my PC to the HDMI 1 port on my C1 and then run an HDMI from eARC on my C1 to my Onkyo).

1. Why is the PC port on the Onkyo NR7100 not working? Why do I start to see the PC boot but then I lose the signal? Why is it that HDMI input 1 works if I swap the settings to make it PC input rather than BD/DVD, but won't work otherwise? Am I doing something wrong or is the AVR faulty?
   
   
2. Why can I not get Gsync to work through the Nvidia Control Panel despite getting 4k/120hz/HDR? It doesn't appear as an option. Through the NVCP settings, it reads the display as "Onkyo Corporation AV" instead of LG C1. Is there a setting I can change to tell my PC I'm running the LG through an AVR?
   
   
3. A separate, unrelated issue: When I try to select "Direct" as a listening mode on the Onkyo, it won't read my subwoofer. I'm currently running a 2.1 setup, and I only get audio from my Left and Right front speakers. So I select Stereo or Dolby Digital Surround and it reads my speakers and subwoofer, but it sounds like both my speakers and my sub are playing low frequencies -- too heavy on the bass. Can't seem to figure this one out.
   
   
4. When I enable HDR on Windows (Win + Alt + B), my audio cuts out. I have to go to Windows sound settings and select a different sound output and then go back to selecting the "AV Receiver" output.

I know this was lengthy but I tried to include all the details. I was really hoping adding the AVR to my setup would be smooth and effortless but boy was I wrong. I'm debating returning this AVR and just getting an amp or something simpler. I appreciate any support or direction on how to fix these issues. Thank you!

 

[digitalmallrat]

So I've partially resolved my issue. I think the problem with why the PC wasn't displaying is because I had HDMI input 1 labeled as HDMI input 6 and only had 8k Enhanced on for input 6 but not input 1. So I've just plugged the PC into HDMI input 1 and left it labeled as the default BD/DVD and turned on 8K Enhanced for all ports. But I still can't get Gsync to work. I'm communicating with Onkyo support and so far their solution has been to separate audio from video, by connecting my PC to my C1 and then using my C1's eARC to my receiver... but this is the very thing I was looking to avoid with this unit. If anyone has any tips, please let me know!

 

[digitalmallrat]

For anyone who comes across this thread with a similar issue, here's what I did to resolve my problem:

1. I think the problem with why it wasn't displaying is because I had HDMI input 1 labeled as HDMI input 6 and only had 8k Enhanced on for input 6 but not input 1. So I've just plugged the PC into HDMI input 1 and left it labeled as the default BD/DVD and turned on 8K Enhanced for all ports. This allowed the PC to display once Windows loaded.
2. To get Gsync to work, I had to change a setting within NVCP: under "Adjust desktop size and position", under the "Scaling" tab, under the drop down menu of "Perform scaling on:" set it to "Display" and not "GPU". While it's on "GPU", for whatever reason, Gsync won't show up as an option/won't work and my PC's VRR is disabled. If I select "Display", Gsync is an option and I can enable it and VRR is enabled.