My Series X is loud compared to my partners

This is an uncomfortable problem, but not a game breaking one per se.

My partner and I have had Series Xs since launch. Since then hers has been nigh silent in all circumstances, from initial launch to playing Series X games for hours non stop. It's perfect.

Mine has been comparatively disappointing. It is not earth shatteringly loud, but it is substantially louder than hers. It can be heard from across the room, albeit only faintly, as soon as it is turned on. And once it boots a game, it is what I would describe
as several times louder. Even when she is playing a game on hers but mine is newly booted, mine is louder than hers.

It's still not earth shatteringly loud, but consciously irritating, especially when we have another Series X in the room which is just so quiet no matter what is thrown at it. It's the fan. It's not hitting anything or cracking. It's just always audibly
whooshing no matter what it is doing. It always sounds like it is dealing with an unduly large amount of air.

It has a limited Microsoft warranty, having been bought directly from MS. I would really like to get it replaced with another one, or "fixed" if such a thing is possible, but I am concerned that I will send it to them, they'll say "eh - it's good enough"
and just send it back. Then it has endured travel wear and tear for nothing and I have to carry it by foot for 30 minutes to send it, which is very awkward at best given the lockdown for coronavirus here.

It does work, if all you want it to do is play games no matter the mechanical noise, but I bought what I thought was supposed to be an especially quiet console and I can hear from my partner's Xbox Series X that it is supposed to one.

It's just off-putting to play and when I do manage to play it is encouraging me to not actually play Series X games to try and keep it quiet. Even with headphones I can hear it when the games quiet down a bit, like during home base in Vermintide. And I don't
like headphones anyway because I have tinnitus.

Does anybody have any advice? Is there anything others have done in a similar situation to make the Xbox quieter? Something I can try to self repair without breaking warranty? Or should I, once lockdown is over, just send it back? How good are Microsoft
at believing that this problem is real and not just imagined. If they did a five minute test without another Xbox to compare, they might think nothing of it.

It's just very disappointing. I was so hyped up to replace my Xbox One OG and now I don't even like playing my new Series X because I can tell there is something wrong with it and am anguished about whether or not to send it back.

P.S. Both consoles are in the same room, on the same kind of surface, and equally well ventilated.

:)