The secret with the PlayStation 5's and Project Scarlett's ultra-fast SSDs might not lie with the actual PCIe generation of the drives themselves, but how that storage is optimized with software and additional hardware, such as cache modules.
The storage in next-gen consoles could end up utilizing something very similar to Intel's Optane M.2 modules. This might be somewhat expensive and nullify the cost-effective argument against PCIe 4.0, at least for the custom module solution, but it could also supercharge data speeds at relatively low capacities.
We know that Optane won't actually be used in next-gen consoles (which, of course, are powered by AMD), but we'll use it to demonstrate how this tech works and what it means for gaming.
Intel's consumer-available Optane modules have one simple premise: To make your most frequently-used data load faster.
The stick determines what programs and data you access and use the most, and prioritizes the data by caching it on Intel's proprietary 3D XPoint memory. That way, the CPU can access the data directly, which is great news for developers, especially when they need to rapidly move huge scattered blocks of data.
This is called memory caching. It's different from tiered storage, which we'll get to later on.
These types of modules were meant to complement existing storage, not replace it. They can sit in a build with multiple drives, including a setup with an HDD and SSD solution, whereby the HDD's speed is somewhat counteracted by the fast caching of the module and the SSD's overall data rates.
Optane is a cache memory stick with built-in DRAM and storage memory that sort of bridges communication between storage, processor (CPU, GPU), and system RAM. It streamlines the system in a more direct and seamless path to maximize speeds, and stores often-used data from the SSD onto its memory cache, which is then fed directly to the CPU itself.
"When this new memory media is installed between the processor and slower storage devices (SATA HDD, SSHD, SSD), the computer can store commonly used data and programs closer to the processor. This allows the system to access this information more quickly, which can improve overall system responsiveness," Intel says about its Optane modules.
Remember, these kinds of modules only hold the prioritized data on its cache, whereas the bulk of your system's data is stored on another drive, whether it be mechanical HDD or NAND SSD (or both). Optane isn't storage, more of a kind of memory card that holds the most important data.
The 3D Xpoint memory in Optane is Intel's own version of an SCM, or storage-class memory, which is typically used in enterprise servers to cache immense data loads.
Sony has its own SCM solution using ReRAM, or Resistive Random Access Memory, and it could be the secret sauce behind the PlayStation 5's ultra-fast solid state drive.