Xbox Series X SSD: DRAM-less PCIe 4.0 NVMe with up to 3.7GB/sec speeds

Microsoft's new next-gen Xbox Series X may use a DRAM-less SSD with up to 3.75GB/sec read/write speeds.

12 minutes & 13 seconds read time

The Xbox Series X may use a DRAM-less PCIe 4.0 M.2 SSD with up to a 2TB capacity that delivers up to 3.75GB/sec read and write speeds, all built with Phison's newer PS5019-E19T flash memory controller.

Xbox Series X SSD: DRAM-less PCIe 4.0 NVMe with up to 3.7GB/sec speeds 4

A bit ago we reported the Xbox Series X could use Phison's potent flash memory controllers--custom chips that communicate with a host CPU--to enable high-end transfers. Now Xbox Series X's flash controller has apparently been identified as Phison's PS5019-E19T chip, giving us an idea of the system's max storage performance and what to expect from the console.

The news comes from Phison software engineer Jerry Lou's LinkedIn page, which specifically outs the Xbox Series X's solution:

"Designed flagship PS5016-E16, world's first PCIe Gen4x4 NVMe SSD solution, and PS5019-E19, DRAM-less PCIe Gen4x4 NVMe SSD installed in Xbox Scarlett by hosting scrum ceremonies as scrum master."

Based on this, the Xbox Series X's SSD can come up in to 2TB capacities, and theoretically deliver up to 3.75GB/sec sequential reads and writes, and hit up to 440K IOPS read and 500K IOPS writes. That's roughly 36 times faster than the 100MB/sec average read/writes in the stock 5400RPM Xbox One hard drives.

The E19T is a 28nm chip with an ARM Cortex R5 CPU uses PCIe 4.0 across 4x lanes to hit these max thresholds, and uses the M.2 2280 spec on the NVMe 1.4 protocol.

Xbox Series X SSD: DRAM-less PCIe 4.0 NVMe with up to 3.7GB/sec speeds 34

Specs of the Phison PS5019-E19T flash memory controller from the 2019 Flash Memory Summit.

Remember, just because the Phison E19T controller can hit these speeds doesn't mean the Xbox Series X's SSD actually will. These are the maximum performance values that E19T-equipped drives can achieve.

There's still lots of unknowns that will determine overall storage perf, including what kind of flash memory the SSD uses (will it be faster but more expensive SLC, or Single-Layer Cell flash, or the slower but higher-density and lower-cost QLC, or Quad-Layer Cell flash?).

There's even more to the Xbox Series X's SSD, though.

The E19T flash controller is for DRAM-less storage, indicating the Xbox Series X will likewise use a DRAM-less SSD. Most SSDs come with DRAM embedded alongside flash memory, which is leagues faster than the actual flash storage chips. The DRAM communicates directly with the CPU and storage to locate and shift data back and forth.

These controllers instead use Host Memory Buffers and tap the DRAM on a host device. This means the Xbox Series X will have a bit of DRAM exclusively allocated for storage data mapping and fetching.

Using a DRAM-less drive allows Microsoft to keep the costs of manufacturing down while not having to sacrifice PCIe 4.0 speeds.

As for Microsoft's promises of a "new generation of SSDs," we're really not sure on this front. We've speculated the console could use a combination of ReRAM or Optane-like cache to complement the SSD, but this seems unlikely. It's more likely the console's custom Zen 2 CPU synergizes directly with the PCIe 4.0 SSDs, possibly wrapped in firmware designed special for next-gen memory paging.

Here's what Microsoft's said about the Xbox Series X's SSD so far:

"We've created a new generation of SSD. We're actually using the SSD as virtual RAM. We're seeing more than 40x performance increases over the current generation," Microsoft said in the Project Scarlett E3 2019 reveal video.

"The combination of the SoC and the solid state drive are really what gives you a totally new experience."

"Now we can take all of that power and apply all of that back into the scene, and generate more life into that world and bring it to the gamer in a seamless way."

We won't know full Xbox SX SSD details until Microsoft announces them, but now we have a better idea of what to expect from the system.

Xbox Series X is due out by Holiday 2020. No pricing has been announced.

Check below for confirmed specs and details, and a huge content listing of everything we've heard about Xbox Series X so far:

Xbox Series X confirmed details (Formerly Project Scarlett):

  • 8-core, 16-thread Zen 2 CPU
  • Navi GPU on RDNA architecture
  • Highly customized 7nm SoC from AMD
  • GDDR6 memory
  • 2x Xbox One X's 6TFLOPs of GPU perf
  • 4x CPU power of Xbox One generation
  • Can deliver up to 40x more performance than Xbox One in specific use cases
  • Adaptive sync supported
  • Super-fast SSD that can be used as VRAM
  • Supports 8K resolution (likely media playback)
  • 120FPS gaming
  • Variable refresh rate (adaptive sync/FreeSync)
  • Variable Rate Shading
  • Raytracing confirmed with dedicated raytracing cores
  • Backward compatible with thousands of Xbox, Xbox 360, and Xbox One games
  • New controller with a dedicated share button
  • Compatible with Xbox One accessories

Lockhart (Unconfirmed lower-end Xbox Series hardware)

  • 1440p 60FPS
  • No disc drive
  • Super-fast SSD that can be used as VRAM
  • 7nm AMD SoC w/ scaled-down 8-core, 16 thread Zen 2 CPU at 3.5GHZ and Navi GPU
  • Lower GDDR6 memory pool (Possibly 12GB)
  • ~6-8 TFLOPs of power?
  • Aims to rival PS4 Pro/Replace Xbox One S
  • Full backward compatibility with all Xbox One games
  • Cheaper MSRP

Anaconda/Xbox Series X/Project Scarlett

  • 4K 60FPS
  • Disc drive with 4K UHD playback
  • Super-fast SSD that can be used as VRAM
  • 7nm AMD SoC with 8-core, 16 thread Zen 2 CPU at 3.5GHz and Navi GPU
  • 16GB GDDR6 RAM
  • 12 TFLOPs of power
  • 2x GPU power as Xbox One X/aims to replace Xbox One X
  • Full backward compatibility with all Xbox One games
  • More expensive MSRP

Xbox Series X coverage:

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Derek joined the TweakTown team in 2015 and has since reviewed and played 1000s of hours of new games. Derek is absorbed with the intersection of technology and gaming, and is always looking forward to new advancements. With over six years in games journalism under his belt, Derek aims to further engage the gaming sector while taking a peek under the tech that powers it. He hopes to one day explore the stars in No Man's Sky with the magic of VR.

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