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/us/en/products/docs/chipsets/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?

[porina]

4 minutes ago, rcarlos243 said:

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?

The same way each PC I have is gigabit+ ethernet, but my internet is much lower. Chipset is basically a switch for data. Not everything will be active at the same time so unless you heavily hit multiple things at once, you're unlikely to limit the connection. Even when limited, some things may work a bit lower.

[Jax_the_gnome]

I think you are looking at different units, and It's not. None of the devices use all of the bandwidth all of the time, so it's shared.

 

DMI4.0 x8
15.75GBps
PCIE4.0x 20
40GBps
 

[rcarlos243]

10 minutes ago, porina said:

The same way each PC I have is gigabit+ ethernet, but my internet is much lower. Chipset is basically a switch for data. Not everything will be active at the same time so unless you heavily hit multiple things at once, you're unlikely to limit the connection. Even when limited, some things may work a bit lower.

 

If I put 5x PCIe Gen 4 SSD in RAID 0 and all are connected via the chipset, would I get limited to a max bandwidth of 128GT/s or 16GB/s or 16GBps?

[porina]

6 minutes ago, rcarlos243 said:

If I put 5x PCIe Gen 4 SSD in RAID 0 and all are connected via the chipset, I would get limited to a max bandwidth of 128GT/s or 8GB/s or 8GBps?

About 16 GB/s which is the link between chipset and CPU, if you can find a mobo with connectors available to do that. If you genuinely need that kind of storage bandwidth you should probably be looking at a HEDT/workstation platform with more connectivity. For example, I have 4x M.2 SSDs in a CPU connected x16 slot in my system right now but I don't raid 0.