Ryzen CPU lanes

[Sniperfox47]

Does anyone know how the PCIe lanes on the Ryzen CPUs are laid out? I keep hearing 24 lanes, but are those coming off the CPU, x370, or a total of both?

 

I know on Intel's side x99 has up to 48, up to 40 PCIe 3.0 off the CPU and an additional 8 PCIe 2.0 off the chipset.

 

I know on the z270 platform there's 40 lanes, 16 PCIe 3.0 off the CPU and an additional 24 PCIe 3.0 off the chipset.

 

If the AM4 platform only offers 24 lanes I'm still quite worried about the state of the motherboards, but if it's a total of 48 (24 off the CPU, and 24 off the x370 chipset) then that's another story.

[cj09beira]

2 minutes ago, Sniperfox47 said:

Does anyone know how the PCIe lanes on the Ryzen CPUs are laid out? I keep hearing 24 lanes, but are those coming off the CPU, x370, or a total of both?

 

I know on Intel's side x99 has up to 48, up to 40 PCIe 3.0 off the CPU and an additional 8 PCIe 2.0 off the chipset.

 

I know on the z270 platform there's 40 lanes, 16 PCIe 3.0 off the CPU and an additional 24 PCIe 3.0 off the chipset.

 

If the AM4 platform only offers 24 lanes I'm still quite worried about the state of the motherboards, but if it's a total of 48 (24 off the CPU, and 24 off the x370 chipset) then that's another story.

z270 doesnt have 40 lanes, it has a max of 30 (cpu+ chipset),

ryzen will be the same as skylake, 24 available for expansion cards

[Sniperfox47]

9 minutes ago, cj09beira said:

z270 doesnt have 40 lanes, it has a max of 30 (cpu+ chipset),

ryzen will be the same as skylake, 24 available for expansion cards

No. Z270 has 24 lanes off the chipset plus an additional 16 off the CPU.

 

https://ark.intel.com/products/98089/Intel-Z270-Chipset

https://ark.intel.com/products/97129/Intel-Core-i7-7700K-Processor-8M-Cache-up-to-4_50-GHz

 

They're full lanes with full DMA and aren't passed through a PLX or anything.

 

There's literally a sticky at the top of this subforum explaining this... 

 

[LAwLz]

It seems like Ryzen will have 24 (PCIe 3.0) lanes on the CPU, and 8 (PCIe 2.0) lanes from the chipset (specifically the X370 one, the others have fewer).

Source: Guru3D

[Sniperfox47]

Oh okay. So not quite as many as the Intel platforms but at least the extra 8 will give you some lanes for an m.2 slot or two.

 

I'll be interested to see how feature rich the AM4 boards are then. Wonder what bits they'll drop.

[Exentio]

I really, really wanted to buy a 1700(X), but I need two GPUs (one for gaming and GPGPU and one for KVM GPU passthrough) and a 10Gb SFP+ card, in a mATX motherboard because I have a Carbide Air 240. Ryzen has 24 PCIe 3.0 on the CPU, and 8 PCIe 2.0 on the chipset (6 in my case because mATX motherboards will only have the B350 chipset, which has 6, Gigabyte has planned a X370 mATX motherboard but it's probably out of my budget); the 24 3.0 lanes are 16 dedicated to graphics and 8 assigned to 2 M.2 slots. I'd be fine with 8x+8x on the GPU, but 6x PCIe doesn't exist

[cj09beira]

49 minutes ago, Sniperfox47 said:

No. Z270 has 24 lanes off the chipset plus an additional 16 off the CPU.

 

https://ark.intel.com/products/98089/Intel-Z270-Chipset

https://ark.intel.com/products/97129/Intel-Core-i7-7700K-Processor-8M-Cache-up-to-4_50-GHz

 

They're full lanes with full DMA and aren't passed through a PLX or anything.

 

There's literally a sticky at the top of this subforum explaining this... 

 

thoses 24 from the chipset are multiplexed, with means they are limited to the max bandwidth of the DMI connection with is just 4 lanes, 16+4= 20

20 lanes is the max that the cpu can provide in terms of bandwidth, 

[Sniperfox47]

20 minutes ago, Exentio said:

I really, really wanted to buy a 1700(X), but I need two GPUs (one for gaming and GPGPU and one for KVM GPU passthrough) and a 10Gb SFP+ card, in a mATX motherboard because I have a Carbide Air 240. Ryzen has 24 PCIe 3.0 on the CPU, and 8 PCIe 2.0 on the chipset (6 in my case because mATX motherboards will only have the B350 chipset, which has 6, Gigabyte has planned a X370 mATX motherboard but it's probably out of my budget); the 24 3.0 lanes are 16 dedicated to graphics and 8 assigned to 2 M.2 slots. I'd be fine with 8x+8x on the GPU, but 6x PCIe doesn't exist

A bunch of the x370 boards seem to be putting all of the PCIe lanes on 3 16x slots (at 16x/8x or 8x/8x/8x), so I'd imagine you can probably find an mATX board that has the slots you need.

[ian666]

Looks like X370 motherboards are not capable of running pcie cards in x16/x4 @3.0 configuration, they allow only x16/x0 or x8/x8 !!!. This is bad because i have Intel 750 NVMe SSD in form of PCI-E 3.0 x4 card.

 

Checked both top Asus and MSI motherboards, both got this issue (x16/x0 or x8/x8 only). Running graphics card at x8 have some impact (Linus tested it on old GTX980 SLI and we had like 34 vs 37 fps at 4K. With upcoming HBM2 graphics cards or 1080Ti this can translate to like 68 vs 74 fps and this is a bit too high (probably difference between stock 1080Ti and factory overclocked FTW2 for 80 bucks more).

[NumLock21]

We kept on hearing that Ryzen has 24 lanes, but it wasn't officially from AMD themselves. Need to wait until AMD put more details up, because right now it's all over the place.

 

The pics above is from Crosshair VI Hero. It's the only sections in the entire spec sheet, that says "AMD Ryzen", assuming whats under that, runs off the Ryzen CPU. And what's under the X370 chipset, runs off the chipset. Their 7th Gen APUs, is confirmed to have just 8 lanes.

Here is one of the 7th gen apu: http://products.amd.com/en-us/search/APU/AMD-A-Series-Processors/AMD-A12-Series-APU-for-Desktops/7th-Gen-A12-9800E-APU/202

 

AMD Ryzen with 24 lanes ?

-Expansion slot: 16 lanes used, from the dual x8

-Storage: 4 lanes used for M.2 in PCIe or SATA.

-USB Ports: 4 lanes used for USB 3.0?

16+4+4=24?

 

AMD 7th Gen APU with 8 lanes

-Expansion slot: 8 lanes used. This is all from the CPU.

-Storage: M.2 in SATA mode only, that's correct because there is no more lanes from the CPU

-USB Ports: 4 lanes for USB 3.0? Now that can't be because all of 8 lanes is used up by the "Expansion Slot". So that means it's just says it supports 4x USB 3.0. If this is the case then. On Ryzen, that 4x USB 3.0 isn't using any cpu lanes and therefore

Ryzen only has 20 lanes?

 

 

full spec

https://www.asus.com/us/Motherboards/ROG-CROSSHAIR-VI-HERO/specifications/