Xbox Series X Storage Expansion Card revealed, promises performance match with internal SSD

Series X External
Series X External (Image credit: Microsoft)

What you need to know

  • The Xbox Series X Storage Expansion Card will hook up to the slot on the rear of the console.
  • Promises identical performance to the internal SSD.
  • 1TB custom solution built in partnership with Seagate.

As part of the massive data dump on the Xbox Series X the mystery of the storage expansion slot on the rear has been made a little clearer. The slot will be used for the Xbox Series X Storage Expansion Card (yes, what a mouthful), a custom storage solution built in partnership with Seagate.

Source: Microsoft (Image credit: Source: Microsoft)

Inside the console, we'll be getting a 1TB NVMe SSD for storage, but given how big games are going to get in the next-gen, this won't go very far. So, Microsoft has designed a solution to expand that without the necessity to go inside the console and start fiddling with things we shouldn't really be fiddling with. For now Microsoft has only officially confirmed a 1TB Storage Expansion Card, but apparently larger sizes should be coming in future.

It's not a replacement for external USB hard drives, as those will continue to be supported, but the Storage Expansion Card is promising identical performance to the internal drive, as this outline from Microsoft indicates, recommending that Series X optimized games aren't played from a USB hard drive for optimal performance.

Built in partnership with Seagate, this 1 TB custom storage solution expands storage capacity of Xbox Series X with the full speed and performance of the Xbox Velocity Architecture Previous generation Xbox titles can still be played directly from external USB 3.2 hard drives. However, to receive all the benefits of the Xbox Velocity Architecture and optimal performance, Xbox Series X, optimized games should be played from the internal SSD or Xbox Series X Storage Expansion Card.

And as the Digital Foundry team points out, the Xbox Series X utilizes PCIe 4.0 to connect both the internal and external SSD storage directly to the CPU. So far we've only seen PCIe 4.0 used on AMD's X570 platform on PC, but the data speeds it's capable of are pretty spectacular so we're excited to see Microsoft make use of it in the Series X.

Xbox Series X/S


Richard Devine
Managing Editor - Tech, Reviews

Richard Devine is a Managing Editor at Windows Central with over a decade of experience. A former Project Manager and long-term tech addict, he joined Mobile Nations in 2011 and has been found on Android Central and iMore as well as Windows Central. Currently, you'll find him steering the site's coverage of all manner of PC hardware and reviews. Find him on Mastodon at