One of the major advantages of the PS5 over the Xbox Series X is with respect to the I/O bandwidth. While the latter is limited to 2.5GB/s, the former manages to reach 5.5GB/s, and that’s with uncompressed data. With proper file compression in place, you can expect as much as 8-9GB/s. However, the Series X might be capable of more than just 2.5GB/s. In a recent interview, David Springate, the Technical Director of Dirt 5 claimed that the console is capable of transferring up to 10GB in just two seconds.
We look at all of these things all of the time. I can’t promise which stuff is going to come in future patches, because we have to balance loads of different things, but it might. That’s the best I can do. In terms of fast storage on Series X, I think that hardware is great, I worked on it with Microsoft early on and provided some feedback to them. I looked at the speed that we could get from it, you can get 10GB in two seconds in my personal early tests, it may well be able to do way better than that.
And that was without the compression in the hardware, that was just raw.
And yes, that’s the raw I/O bandwidth we’re talking about here, not compressed. When he was asked why MS’s specs peg the Series X at 2.5GB/s, he had the following to say:
The way to get the most out of fast storage on all platforms is to make many requests at once. You want to load five hundred textures, forget loading one texture, you want to load them all. That then gives some challenges to how you lay out your data. You need to know where they’re going to go in memory, you need to know what is it you need before you ask for it. That’s a challenge, it’s not hardware, it’s not the API from Microsoft or Sony, it’s an engineering challenge. We’re very close, we’ve done loads of testing, it’s not something I’m gonna come to saying it’ll come in a patch but it’s something I’m very interested in personally.
What he basically means is that with proper I/O request optimization (read: DirectStorage), you can get a much higher effective bandwidth. DirectStorage is part of DirectX12 Ultimate which is the common API on PC and the Xbox. It reduces the I/O load on the CPU, all the while boosting transfer speeds by allowing for a much higher number of I/O requests on modern PCIe 4.0 SSDs. DirectStorage sends batch I/O requests while earlier every I/O request big or small was individually sent, adding unnecessary load to the processor. This is exactly what I’d predicted in a post earlier this year: