PCie Talk (Speeds)

[midiman]

I have always struggled with math, and some numbers and conversions we use today are mind-boggling.

Now I am starting to look back on 1GB Hard Drives with fondness.

When it comes to calculating speed and throughput, I'm terrible.

I'm trying to understand what we can and can't get from our PCs.

This may require a bit of Maths and Understanding, but here goes.

For example.

We have all seen the headline speeds of SSD,s NVMe, and so on.

But how do we make sure we get the actual value?

This is where PCIe versions and lanes come into effect.

I have read that most NVMEs use 4 PCIe Lanes.

If true, and using the PCIe 4.0 standard, 16TB/s x 4 = 64TB/s converted to GB = 128GB/s.

This would be the maximum theoretical throughput available to the device.

If correct, that is pretty quick, but the weakest link will be the drive the data goes to, and the speed will drop to the drive's maximum value.

Thanks

 

[Dg834man]

If true, and using the PCIe 4.0 standard, 16TB/s x 4 = 64TB/s converted to GB = 128GB/s.

16GT gigatransfers per lane the throughput is 1.969 GB/s x1 and 31.508 GB/s x16

 

[Tetras]

If true, and using the PCIe 4.0 standard, 16TB/s x 4 = 64TB/s converted to GB = 128GB/s.

The transfer rate for PCI-E 4.0 is 16 Gb/s (Gigabits per second).

16 Gbit has to be divided by 8 to get the Gigabytes figure, which is 2 (2GB).

I have read that most NVMEs use 4 PCIe Lanes.

If true, and using the PCIe 4.0 standard, 16TB/s x 4 = 64TB/s converted to GB = 128GB/s.

If you want the figure for 4 lanes, then it is 8GB, which is why PCI-E 4.0 drives have read figures below 8000 MB/s.