What’s the Xbox Series X mystery port? Here’s one insider’s theory

(Image credit: Microsoft)

The mystery port on the back of the Xbox Series X may have been identified. Among several typical ports spotted in recently leaked images of the upcoming console, there was one that no one seemed able to figure out. Thurrott’s Brad Sams, a noted Microsoft insider, says he now knows what the mysterious long port on the back of the Xbox Series X is. Though he initially speculated the port was for diagnostics, he now says he was incorrect.

“That port is for storage expansion, according to people familiar with the company’s plans,” said Sams, and it’s intended to offer Xbox Series X “a work-around as games continue to expand in size.” 

Sams pointed to the fact that games are growing enormous in size, citing games like Call of Duty and Grand Theft Auto 5 which routinely balloon to take up more than 100 GB alone on players’ hard drives. Even if the new consoles launch with 1 TB hard drives, that would mean players could only install about nine or ten such games. 

An expandable storage port such as this could be preferred over the kind of USB add-on players already use with current generation consoles because it would offer higher speeds than the USB port - not to mention it would allow Microsoft to sell players expanded hard drive space directly rather than leave them to buy from another manufacturer. The fact that this port could not be identified points to it being proprietary, not yet revealed tech from Microsoft, though with traditional USB ports still available, it may be that consumers will still be able to choose the way they upgrade their storage, even if Microsoft positions their solution as the best.

The images of a Series X prototype first appeared online two weeks ago which revealed several interesting bits of information. Not the least of which was an intact serial number, which likely led to the leaker getting in trouble behind the scenes. Ouch. In better news, however, it gave fans a closer look than that which we got during the console’s reveal at The Game Awards. The back of the prototype included two USB-A ports, an ethernet port, a single HDMI Out port, optical audio, and a power port. 

The absence of an HDMI out port signals a reformed Team Xbox, argues Josh West.

Freelance Journalist

Mark Delaney is a prolific copywriter and journalist. Having contributed to publications like GamesRadar+ and Official Xbox Magazine, writing news, features, reviews, and guides, he has since turned his eye to other adventures in the industry. In 2019, Mark became OpenCritic's first in-house staff writer, and in 2021 he became the guides editor over at GameSpot.