By: anon (spam.delete.delete.delete@this.this.this.spam.com), April 19, 2019 1:03 am
Room: Moderated Discussions
PiedPiper (not.delete@this.likelyh.com) on April 18, 2019 7:33 pm wrote:
>
> > Are we looking at the same specs? It says 3500 MB/s for both for me.
> > Either way that's limited more by the controller, the number of chips and the interface rather
> > than the NAND. They could surely build a controller that would squeeze more out of the MLC, but
> > what use is a controller that can get 5000-6000 MB/s read speeds with a PCIe 3.0 x4 interface?
>
> given we know it's zen 2, i'm pretty sure it would be PCIe 4.0
> x4, which changes the max theoretical BW discussion a lot.
I was refering to current SSDs where theoretically the MLC/TLC NAND would be faster than QLC, it just makes no sense to beef up the controller for that when you're limited to less than 4000 MB/s by the interface, resulting in realistically ~3500 MB/s. Of course that changes with PCIe 4.0, but the argument that TLC and QLC both offer the exact same read speed because they can both saturate PCIe 3.0 x4 is bullshit.
But yes, that could be the marketing speak. Ignore the existence of SSD PCIe cards, ignore the fact that PCIe 4.0 x4 will be available for PCs before that console launches and just claim that you've got "more raw bandwidth than anything available for PC right now". Sounds better than "next year we'll have what PCs will have this year" but isn't.
>
> > Are we looking at the same specs? It says 3500 MB/s for both for me.
> > Either way that's limited more by the controller, the number of chips and the interface rather
> > than the NAND. They could surely build a controller that would squeeze more out of the MLC, but
> > what use is a controller that can get 5000-6000 MB/s read speeds with a PCIe 3.0 x4 interface?
>
> given we know it's zen 2, i'm pretty sure it would be PCIe 4.0
> x4, which changes the max theoretical BW discussion a lot.
I was refering to current SSDs where theoretically the MLC/TLC NAND would be faster than QLC, it just makes no sense to beef up the controller for that when you're limited to less than 4000 MB/s by the interface, resulting in realistically ~3500 MB/s. Of course that changes with PCIe 4.0, but the argument that TLC and QLC both offer the exact same read speed because they can both saturate PCIe 3.0 x4 is bullshit.
But yes, that could be the marketing speak. Ignore the existence of SSD PCIe cards, ignore the fact that PCIe 4.0 x4 will be available for PCs before that console launches and just claim that you've got "more raw bandwidth than anything available for PC right now". Sounds better than "next year we'll have what PCs will have this year" but isn't.