Does the Xbox series X support a 100hz monitor?

Unfortunately no. You would only be able to use 60Hz,

Can't say for sure. This is an older HDMI 2.0 monitor. While most work, some of these displays limit the HDMI refresh rate to 100Hz, which would make 120Hz impossible.

You likely won't find this information any many reviews as Display Port is the common way to connect these displays to the main system they were designed for, PCs. Connecting gaming monitors to consoles in a recent thing, and not all monitors work well with Series X over HDMI. Just because the specs say 165Hz, doesn't mean you're guaranteed to get 120Hz over HDMI.

These monitors however, are all compatible with Xbox Series X|S https://www.rtings.com/monitor/reviews/best/xbox-series-x

In that case I highly recommend you see the monitor/TV in action with the console. That way you can verify that the monitor does support 120Hz on the Series X.

The Rtings website's reviews of Series X compatible monitors is a great way to start your search. These are professional TV/monitor reviewers, they test everything!

Hi,

Are you talking about this Monitor?

https://www.rtings.com/monitor/reviews/samsung/odyssey-g5-c34g55t

According to that review the max refresh over HDMI is only 100Hz





Also, it's not strictly a 1440P. This monitor is an ultra wide 3440 x 1440. a True 16:9 aspect 1440P monitor would be 2560x1440. Xbox does not support ultra wide so it will stretch the 2560x1440 to fill the display. Since monitors work best when running at their native resolution the picture will appear soft and odd looking.

There are many fine monitors you can use on the Xbox Series X, unfortunately, this is not one of them.

You have several setups.

This because the console, like was said above will support up to 8K with 120hz - this means that the
maximum performance, is up to the developers to use all that power, some will some wont. You gonna see some games supporting
8k/60hz, others 8k/100hz or 8k/120hz, or the ones that cant or wont use all the power will use like
4k/60hz or 4k/100hz or 4k/120hz.

I know like you said a 8k or 4k/120hz monitors or even TV's are a lot expensive for now, and if you cannot wait for the launch, for a xbox one X you should look for a 4k/60hz monitor, and if you can spend more try look for more hz. But yes for the series X
you will spend more money in a monitor or TV.