brand new xbox one x temperature reaches 70c+ while downloading games

The first thing you found out is that your Xbox has such a temperature. The second thing is the sign that the Xbox would need to be cleaned from the dust, put a new hot-conductive paste.

Not sure dust would be an issue here, as it is brand new. Plus you shouldn't really be opening it up to replace heat paste, that would void the warranty, for starters.

Are you measuring the air at the exhaust port or trying to shoot thru the grates and measure component temps? The air at the exhaust should be pretty warm and so should the heatsink, that means they are working as intended.

Also, are you playing digital games or disk based games that are being patched? If physical disk, they do tend to spin up often during patching. If not, then I'd concur, I would probably exchange it.

Hello Steven,

being that you recently purchased the console we recommend taking it back to point of purchase and exchange the console for different one. Sounds as there could be some internal issues with the hardware on the console you have. If you don't want to do that
and want to get it repaired you can do so at
Device support.

Thanks,

Brad

That's strange, my console gets hot only when playing games of course, I can clearly hear the fan sometimes but it's not annoying.

You sound like a professional so I guess it is already placed in a ventilated area.

Please if it is brand new, return the console to the shop where you bought it and ask for a replacement.

If for some reason it is unavailable, reach the
xbox support team and ask for a replacement.