ASM2824 PCIe switch on PCI-e 2.0, how will it behave?

[kokosnh]

hello 

Have anyone be playing with ASM2824 PCIe switch?

I have Asus P8Z68-V PRO and i7-2600K, I'm considering buying a PCIe card with ASM2824 switch for 4 x PCI-e 3.0 x4 NVMe SSD https://pl.aliexpress.com/item/4000800378079.html  
but i don't know how will it behave on PCI-e 2.0 x8 or x4 slot in motherboard. Will the SSD have still PCI-e 3.0 x4 link, only limited to motherboard connection PCI-e 2.0 x8 (~3200MB/s)?  or will it fallback to PCI-e 2.0 x4 (~1600MB/s) for the SSD? 

Will there be penalty on 4K, or access times for the SSD?
I recently bought intel x520-da2, and had to remove one of my M.2 NVME SSD ( on PCI-e -> M.2 adapter ), from PC. 

Now the intel x520-da2 is in white PCI-e x16 (2.0 x8 speed)

 

 

 

 

 

 

[NewMaxx]

Although it states x16 PCIe 3.0, the upstream from the ASM2824 is actually x8 PCIe 3.0 (~6500 MB/s). So it'll just be bottlenecked by x8 PCIe 2.0 (about half that, close to x4 PCIe 3.0 speeds). If the PCIe slot is x4 PCIe 2.0 electrically then you will be further limited.

[kokosnh]

8 hours ago, NewMaxx said:

ASM2824 is actually x8 PCIe 3.0 (~6500 MB/s).

 I know, I already read the spec, that's why I said

 

23 hours ago, kokosnh said:

Will the SSD have still PCI-e 3.0 x4 link, only limited to motherboard connection PCI-e 2.0 x8

I know what the overall speed will be (it's 4000MB/s on 8b/10b so ~3200MB/s), I don't know if the SSD will get PCIe gen 2.0 or 3.0, when i connect it to PCI-e 2.0 slot. 

[Kilrah]

The switch is creating new PCIe 3.0 lanes so it should be that between chip and SSD.

[kokosnh]

 

Switch on PCI-e 2.0 x 8 directly to CPU 

 

 

Switch on PCI-e 2.0 x 4 through chipset 

 

 

Adapter PCI-e -> M.2 on PCI-e 2.0 x 4 through chipset 

 

 

 

The funny thing is, that on PCI-e 2.0 x4 through chipset, it's actually better to have a PCI-e switch between, then going strait to PCI-e via PCI-e -> M./2 adapter.