Silicon Motion Preps PCIe 5.0 SSD Controllers For Blistering Next Gen Storage
It may seem hard to believe, but storage makers are already approaching the limits of the PCI Express 4.0 bus in a typical NVMe drive, with the latest controller designs pushing transfer speeds in the neighborhood of 7 gigabytes per second (GB/s). That being the case, Silicon Motion is already at work developing controllers that leverage the PCI Express 5.0 bus.
Before we get to that, let's go over the bandwidth limits of each PCI Express specification to date, starting with PCI Express 1.0...
- PCIe 1.0: 2.5GT/s transfer rate, 250MB/s per lane bandwidth, 4.0GB/s x16 bandwidth
- PCIe 2.0: 5.0GT/s transfer rate, 500MB/s per lane bandwidth, 8.0GB/s x16 bandwidth
- PCIe 3.0: 8.0GT/s transfer rate, 1GB/s per lane bandwidth, 16GB/s x16 bandwidth
- PCIe 4.0: 16GT/s transfer rate, 2GB/s per lane bandwidth, 32GB/s x16 bandwidth
- PCIe 5.0: 32GT/s transfer rate, 4GB/s per lane bandwidth, 64GB x16 bandwidth
A typical high-performance consumer SSD ships in an M.2 form factor with an NVMe interface, operating at x4 speeds (four lanes of traffic). That means the ceiling for today's PCIe 4.0 models can, in theory, reach a maximum speed of 8GB/s.
Overhead cuts into the theoretical maximum, and other factors influence top speeds, such as the type of NAND flash memory and the SSD controller chip. But with drives like Samsung's SSD 980 Pro offering transfer speeds of up to 7GB/s, there is not much headroom left. Not until PCIe 5.0 arrives in earnest, which will pave the way for SSDs that are twice as fast.
During a recent conference call to discuss its fourth quarter earnings, Silicon Motion indicated it has PCIe 5.0 controllers in the pipeline, though they will not be coming out this year.
So we are about a year and a half away from seeing PCIe 5.0 controller chips from Silicon Motion. Meanwhile, Intel is set to introduce platform support for the PCIe 5.0 specification when Alder Lake arrives later this year, with its 600 series chipset. Same goes for its next-gen Xeon Scalable "Sapphire Rapids" CPUs for the server sector.
It will be interesting to see what kind of time line other controller makers are working with, and in particular Phison, which introduced its 8-channel E18 SSD controller last November for blazing fast PCIe 4.0 SSDs. The E18 controller supports read speeds of up to 7.4GB/s, and wrote speeds of up to 7GB/s, in capacities up to 8TB. For that, you will need a supported platform, such as AMD's X570 or B550 chipset with a Ryzen 3000 or 5000 series CPU, or one of Intel's upcoming Rocket Lake-S CPUs paired with a 500 series chipset.
