https://wccftech.com/xbox-series-x-storage-expansion-slot-cfexpress-card/

Back in January, after a bit of a false alarm during the AMD CES presser, the Xbox Series X’s back ports were revealed. It was mostly stuff you’d expect –  the usual HDMI out, USB, ethernet, and optical audio ports, but there was also a mystery slot that nobody could quite identify. Some speculated it might be for debugging purposes, but it seems that’s not the case.

According to solid Xbox insider Brad Sams at Thurrott.com, the mystery slot is, in fact, for memory expansion. That makes sense, as both the Xbox Series X and PS5 will take advantage of speedy solid-state drives, with a side-effect being you’ll no longer be able to plug any old cheap portable hard drive in for extra storage. Both of the new consoles are going to have to come up with novel storage solutions.