any one else having sound issues in apps at 4k 120hz

I would look into your monitor and call DELL not Microsoft. I also have a One X and have never had any problems, as soon as select 120hz it automatically drops me down from 4K to 1440p. You must be misunderstanding something about your monitor as there
must be a defect of some sort or your monitor does not support 1440p at 120hz.

For reference, before responding I booted on both my One X's. One is connected to a Samsung 4K QLED and I had no problem switching from 4k 60 to 1440p 120. My other X is connected via an LG 4K monitor and again when selecting 1440p OR 120hz it automatically
selects 1440p or 120hz without any issues.

Hello, LeonEmilio. I'm Arturo, and I'll be glad to provide assistance with your inquiry today.

Yes, you can use any HDMI cable with a Series X. Just make sure the cable you get is a high quality one.

In addition to that, it is important to mention that if you want to use 120Hz @ 4K, you need an ultra-high speed HDMI cable that supports HDMI 2.1.
The one that came with the Series X is an ultra-high speed cord.

More information about 4K @ 120Hz can be found here:

https://support.xbox.com/help/hardware-network/display-sound/4k-gaming-at-120hz

I hope you find this answer helpful to your inquiry. However, I'll remain attentive to any other one you may have.

Regards,

Arturo.

Welp I've discovered the issue.

It's being caused by setting my xb to 120fps.

If I drop it down to 60fps the issue doesn't occur.

My TV is set up for 4k 120hz and hdmi 2.1. both my cables, one of which came with the xb, are 8k ultra 2.1 hdmi.

I'm not sure if this is the xbox or the tv as I have nothing else to test at 120hz.

Any ideas?

Edit: If I turn 120fps back on but disable atmos or dtx bitstream the problem also stops. Setting bitstream to anything else or turning it off stops the issue.

Microsoft's prior console, the Xbox One X only has HDMI 2.0. Full 120Hz at 4K requires HDMI 2.1 which that Xbox does not have.

HDMI 2.0 does not have the bandwidth for 120Hz at 4K. In any case, there are no games on the older Xbox One X that run at 120Hz (or 120fps). There is enough bandwidth for 1440P at 120Hz, which is why you select this from the menu.

Like you've said, your PC graphics card has HDMI 2.1 which is why you can use 120Hz with this connected your TV.

The Xbox One X simply isn't powerful enough to output pretty much any game at 120Hz, the console will be sending out a 120Hz image, but that doesn't mean that the game will be running at 120Hz.

Its like setting your console to 1080p but displaying on a 4K TV, the TV still shows a 4K image, but that's because the image has been up-scaled to fill the 4K screen.