Can the Xbox Series X support gaming at 3440 x 1440 Resolution at 165hz?

No as it's.not vesa standard

166hz is stamdard

You.can check for console compatible lcd monitors if you look for xbox or ps compatible screens

Xbox does not support 21:9 aspects ratio (also known as Ultra Wide)

The max refresh rate of the Series X is 120Hz. The 165Hz on that display is only for the display port.

That's not a good fit for the Xbox console. You need either a 4K, 1440P or 1080P 16:9 display.

Do not just pick any display. There are loads of reviews online of compatible displays. You just need to do a little research.

the monitor specs show

HDMI (Max. Resolution at Hz)

3440 x 1440 10bit@85Hz
3440 x 1440 8bit@100Hz

as the freesync does not cover the range up to 120hz then i don't think it will be selectable, my screen has freesync up to 165hz over hdmi and DP and is selectable.

your DP port covers up to 160hz, not sure if a hdmi to dp will work as i have never used one but i know they need to be specific version.

21:9 aspect ratio

Hi,

There is your issue. Xbox One only supports 1440P on 16:9 aspect ratios (2560x1440).

Xbox supports your vertical resolution (1440), but not your display's horizontal resolution of 3440.

I have no idea if MS will support 21:9 aspect ratio's on Xbox One in the future, although I believe Series X will.

Hi,

It's not possible on that display. The big reason why is that it isn't a 1440P display, at least it isn't a 16:9 aspect 1440P display, it's a 21:9 Ultra-wide monitor. Xbox only supports 1440P 16:9 aspect ratio displays. These monitors have a resolution of 2560 x 1440, yours has a resolution of 3440 x 1440.

The Asus ROG PG348Q is designed more for PC gaming not console gaming. Unless Microsoft provide support for these types of monitors in the future I'm afraid you're stuck with a maximum resolution of 1080P.