Question Question about Intel chipset bandwidth.

[rcarlos243]

A single lane of DMI 4.0 has a speed of 16GT/s
https://en.wikipedia.org/wiki/Direct_Media_Interface

A single lane of PCIe 4.0 has a speed of 16GT/s
https://en.wikipedia.org/wiki/PCI_Express

Intel Z790 chipset is connected to the CPU through a DMI 4.0 x8 lanes (128GT/s)

https://www.intel.com/content/www/u...ets/desktop-chipsets/z790-chipset-brief.html#


How is it possible to have up to 20x PCIe 4.0 (320GT/s) from the chipset if the chipset only has a bandwidth of (128GT/s) from the CPU?

 

[SteinFG]

The connected devices won't exceed 128GT/s. If you had 5 NVMe drives each capable of 7GB/s and tried to read from all, you won't get more than 16GB/s of combined speed.

 

[rcarlos243]

Let's say I did do a 5x Gen4 NVMe drive in RAID 0 and I maxed out at 16GB/s, how would that affect other things connected to the chipset like the 2.5G ethernet?

 

[SteinFG]

Let's say I did do a 5x Gen4 NVMe drive in RAID 0 and I maxed out at 16GB/s, how would that affect other things connected to the chipset like the 2.5G ethernet?

You'd get some slow ethernet link, and slightly slower NVMe speeds. The ratio between the two is not written in spec anywhere I think, in cases of saturated bandwidth the chipset just tries to make sure everything works at some kind of speed.