PCI-e Lane question

[RadiatingLight]

All of these PCI-e lane questions popping up lately made me want to put a link to a post (not this one) in my sig clearing up all the confusion about PCI-e lanes and how much are available on each chipset, etc.

 

however, I don't want to put in any false information, so I want to check in with you all

 

- a chipset like H110 only has 6 PCI-e lanes, which are 2.0 IIRC. as far as I know, these stack with the 16 lanes your CPU provides, which means that a Z170 motherboard, which is listed as having 20 PCI-e 3.0 ports, will actually have 16 + 20? I'm really not sure about this one.

 

 

 

[stealth80]

https://linustechtips.com/main/topic/462341-skylake-haswell-e-pcie-lane-misconception/

[Electronics Wizardy]

30 minutes ago, RadiatingLight said:

will actually have 16 + 20?

yep.

 

But, the chipset lanes are limited to 4x max(even though you have up to 24).

 

You also are limited by the dmi speed,.

[RadiatingLight]

10 hours ago, Electronics Wizardy said:

yep.

 

But, the chipset lanes are limited to 4x max(even though you have up to 24).

 

You also are limited by the dmi speed,.

So what does that mean?

is there only enough bandwith for 4X Gen 3, but up to 20 can connect and share that bandwith?

[typographie]

11 hours ago, RadiatingLight said:

- a chipset like H110 only has 6 PCI-e lanes, which are 2.0 IIRC. as far as I know, these stack with the 16 lanes your CPU provides, which means that a Z170 motherboard, which is listed as having 20 PCI-e 3.0 ports, will actually have 16 + 20? I'm really not sure about this one.

The CPU has 16 lanes, and Z170 has another 20. The chipset's 20 are limited to PCIe 3.0 4x speed, so it's not like you can do quad-SLI in 8x/8x/8x/8x or something… for purposes of graphics, you have 16 lanes. But you have more that can be used for 4x and 1x devices.

 

H110 has 6 lanes, and they are limited to PCIe 2.0 4x because H110 has a DMI 2.0 connection with the CPU. The rest of the Skylake/Kaby Lake chipsets have DMI 3.0 and thus can get PCIe 3.0 4x bandwidth from those lanes. Your CPU in an H110 motherboard still has it's usual 16 PCIe lanes at up to 3.0 16x.