2 x HDMI - one for video, one for audio?

My current way of connecting my PC to my monitor and speakers, and so far the only way to avoid audio lag, is:

PC --HDMI--> A/V Receiver --HDMI--> Monitor

Works fine, no audio lag and no problems here, but I'm wondering - what would happen if I would want to buy a, let's say, ultra-wide monitor with a 2560x1080 resolution while my receiver only supports regular 1080p?

In other words, would it be possible to set up something like this:

GPU1 --video-only-via-HDMI--> Monitor

GPU2 --audio-only-via-HDMI--> A/V Receiver

...and have zero audio lag? I haven't tried that yet and so far, I don't have an option to try it out, but I'm curious, does anyone know if that's even possible? I mean - to force one HDMI connection to send audio-only, not be seen in the system as a separate monitor and would this introduce audio latency given that this would break the connection between the A/V receiver and the monitor?

You would want to plug your single HDMI cable straight into your monitor and the use the 'coaxial/fibre/spidf' cable for the audio.

You should be able to do it assuming you can define a specific HDMI interface as the audio device. It probably won't work for blu-rays though because of the DRM but for everything else it should be fine.

The problem is that these optical outputs you see in most monitors only have the bandwidth for uncompressed stereo sound. Last time I've tried something different (HDMI to monitor + optical to receiver), I have horrible noticeable audio lag because the PC had to compress everything into DD on-the-fly and that took it a little over 100ms.

That said, it could only work as pass-through IF the sound is already coming out compressed via HDMI :(

Yes, that's the assumption... but is it really doable? ;)

You're right it could screw up HDCP, but then... for Blu-rays I can still use my PS3 and since they're 1080p it wouldn't matter.

Anyway, another alternative I would think of could be using:

PC --DisplayPort--> Monitor

PC --HDMI-audio-only--> A/V Receiver

but there's still the question - will I be able to configure it correctly? In the nVidia Control Panel I can always choose "and audio device" and currently that's GPU 1 via HDMI so... the more I think about it, it seems that all I would need to be able to do is to actually turn off the "second display" to avoid having the system trying to render two screens one of them being the A/V Receiver.

But still - would it lag or not, that's the other big question as I can't stand having audio and video out of sync.

As long as you can specify which HDMI port will be used as your audio device (in the playback devices menu) then you can use that for audio and the other for video. But if you only have one option, as in it doesn't differentiate between ports, then you might need a second video card, or if you have some kind of onboard. You may be able to put the audio over HDMI and use DVI or display port for the video. But you'll have to try it and see. I guess what I'm saying is that there is no reason why the video and audio need to be on the same cable or device, so it should work as long as there is actually a way of doing it.

As for lag, there shouldn't be any. I use HDMI for audio and video via a receiver and I can't see any latency issues.

I already have 2-way SLI so even if I had to run audio through the second card - no problem :)

You don't have a lag as you seem to run it as I do now - one HDMI to the receiver and one out to the monitor so it's still one "chain"... it you know what I mean. So my concern is if I let the monitor do the video and the receiver the audio, given any lack of communication between the two, both would try to minimize input lag so if the audio comes sooner than the video or vice-versa, then I could have a noticeable lag...? I guess? I'm not sure, though.

Anyway, I just noticed that I can actually test this already - hook-up the monitor directly via HDMI and then also the receiver via HDMI-out on the second card and see what options I get and if it lags. I don't have a DisplayPort cable at hand, but I'll get one and try it out later so yeah... sorry for bothering, not sure why I didn't think I can't verify this now. I'll post the results here once I have the data :)

There shouldn't be a lag problem, most people don't run their PC through a receiver and they don't have any problems. Using a separate audio and video device used to and pretty much still is pretty standard so I wouldn't worry about it. Getting lag because the monitor is re-encoding the audio and sending it to the receiver is a different issue.

Weird, coz I used to have HDMI > TV and then SPDIF > Speakers and it was just fine.

Maybe there is something up with your receiver?

Please define "just fine" ;) You mean - you've had uncompressed 5 channel audio streaming through an optical cable (which is physically impossible)?

In my case, I had the PC do the encoding and this introduced a/v sync issues. I', not sure how your screen was handling this - were you feeding it already compressed audio? As again - an optical TOSLINK cable can't carry uncompressed signal for more than 2 channels.

Why can't you use a 3.5mm out?

Because I don't have a 3.5mm input in my receiver.

I don`t know of a real receiver without one what in the world are you plugging into 

It's a Pioneer VSX-1122-K. Here's the rear view: http://i.i.cbsi.com/cnwk.1d/i/tim/2012/03/14/VSX-1122-K_Rear.jpg

Quickest and easiest fix that I can see:


RiteAV 6 Feet 3.5mm to Stereo RCA Male Cable

Most receivers can use hdmi as an audio only source. The benefit is that if you get a projector or big screen you can quickly switch outputs. Plus the DAC in your receiver is better than Your PC. If you get any lag turn off any processing on both the monitor and receiver.

So you're suggesting to use a 4 speaker setup just in stereo? FYI, my original question was whether or not it's possible to use HDMI just for audio while a second HDMI (or DisplayPort) port would be used for video not how to efficiently degrade the sound ;)

Now, I do appreciate the tips, but just saying - it's case closed, thank you for all comments, the solution lies in the settings not in the cables.


Yes this can be done easily. Simply select which device is default for sound.