The NVMe SSDs are very fasy - up to 4GB/s even for a not especially fast drive - because NVMe is an interface that connects to the PCI bus and depending on the PCI version and number of lanes in the NVMe interface (in that interface there are two variations for SSDs, so they can use 2 or 4 PCI lanes, with 4 lanes having twice the bandwidth that 2 lanes have).
The most recent version of NVMe SSDs which use PCIe version 4 can, when using 4 lanes, theoretically reach 8GB/s and there are already drives out there that get pretty close to it.
However some drives of a similar size and connector are not NVMe but actually SATA (same protocol as the older SSDs) and that stuff is limited to about 500MB/s same as the fastest SSDs from a few years ago.
I’ve recently got a mini PC and had to dive again into all this stuff (I’ve been doing the hardware update of my own desktop PCs for decades now and even building them from scratch but haven’t had to look into it for several years) and the tech has really advanced since the earlier SSD days which were not that long ago.
The NVMe SSDs are very fasy - up to 4GB/s even for a not especially fast drive - because NVMe is an interface that connects to the PCI bus and depending on the PCI version and number of lanes in the NVMe interface (in that interface there are two variations for SSDs, so they can use 2 or 4 PCI lanes, with 4 lanes having twice the bandwidth that 2 lanes have).
The most recent version of NVMe SSDs which use PCIe version 4 can, when using 4 lanes, theoretically reach 8GB/s and there are already drives out there that get pretty close to it.
However some drives of a similar size and connector are not NVMe but actually SATA (same protocol as the older SSDs) and that stuff is limited to about 500MB/s same as the fastest SSDs from a few years ago.
I’ve recently got a mini PC and had to dive again into all this stuff (I’ve been doing the hardware update of my own desktop PCs for decades now and even building them from scratch but haven’t had to look into it for several years) and the tech has really advanced since the earlier SSD days which were not that long ago.
Gen 4 isn’t even the fastest any more.
One of the fastest Gen 5 NVME SSDs can do max Sequential read at 14 500 MB/s (theoretical of course, but not far of)