Yousuf Khan wrote:
On 5/27/2018 7:38 PM, Jimmy Wilkinson Knife wrote:
But the SATA is NOT bottlenecked if they'd just use SATA 3.2 (emphasis
on the .2).

And nvme drives are damn expensive.

SATA 3.2 is basically multiple SATA connectors combined into one,
usually 2 connectors, so it's only twice as fast as SATA 3.0. NVMe is 4x
to 8x faster. NVMe drives are only about 10% more expensive than SATA
drives of the same size.

Yousuf Khan

One reason NVMe cannot go faster still, is the size of
the PCIe buffers in the PCIe logic blocks in chipset/CPU.

https://web.archive.org/web/20150628...yload_Size.pdf

(PLXTech was bought out by Broadcom)
http://www.plxtech.com/files/pdf/tec...yload_Size.pdf

"Intel desktop chipsets support at most a 64-byte maximum payload
while Intel server chipsets support at most a 128-byte maximum payload.
The primary reason for this is to match the cache line size for
snooping on the front side bus."

The 2.5GB/sec a Samsung gives, that might be running into
the buffer limitation, and preventing a full 4GB/sec.

You cannot boot from NVMe without BIOS support, so
slapping a PCIe card with an NVMe strapped to it,
is not the full story. Just in case someone gets
excited and wants to add an NVMe to their old
P2B motherboard.

"Todd" has been installing these, and would
probably have more war stories to tell about them.

Paul