What do PCIe Lanes do?

[ThunderRainbow]

Hello guys,

So I wanted to know some more about PCIe Lanes, and it has come to my attention that some processors have 12 PCIe Lanes. Does that mean it can't run a graphics card in a x16 slot?

 

[alexoiu]

Hi,
An example of a 12 lanes CPU?

 

[kraelic]

What cpu comes with 12 lanes? Intel have 16 for graphics and 4 for the DMI link to the chipset, AMD has the AM4 APUs with 8 lanes to the pci express slot.

Anyway, the physical x16 slots with x16, x8, or x4 lanes can run a GPU at full/half/ or a quarter bandwidth. Gen 3.0 doubles 2.0, which doubles 1.0 so a x4 3.0 is equal to x16 1.0

https://en.wikipedia.org/wiki/PCI_Express

http://www.gamersnexus.net/guides/2488-pci-e-3-x8-vs-x16-performance-impact-on-gpus

You can put an x1 card into any slot x1, x4, x8, x16 and it will run at x1

You can put an x16 gpu into an x1 slot with an open end, or use a riser like the miners do and they will run with x1 bandwidth. Though I don't recommend less than an x4 connection for any gpu.

 

[turbopixel]

Here are some very good descriptions too:
> https://superuser.com/questions/843344/what-is-a-pci-express-lane

 

[ThunderRainbow]

Hi,
An example of a 12 lanes CPU?

Well for example the B250 chipset has 12 PCIe lanes

 

[Gam3r01]

Chipset, not processor.
Both the motherboard and the processor have their own PCIe lanes, the chipset routes things like SATA ports, PCIex1 lanes, etc. The processor routes to PCIeX16 lanes for the most part.

 

[kraelic]

Hi,
An example of a 12 lanes CPU?

Well for example the B250 chipset has 12 PCIe lanes

CPU still has 16 for graphics and the 4 lane DMI 3.0 to the chipset. B250 PCH's 12 lanes which go to m.2, x1 slots, built in ethernet, etc. Z170 has 20 lanes. Z270 has 24 lanes.

As far as CPU's, the AM4 APU's have 8 lanes for graphics, Everything else in mainstream has at least 16 lanes. then you have to get into Intel HEDT to get 28, 40 or 44 lane cpus, or AMD Threadripper for 64 lanes.