PCIE Lanes Dilema for the 5000 series CPU

[Mozauk]

I apologize in advanced if this is in the wrong area and/or this post is all over the place.

My current build is a 1st generation threadripper which I was wanting to upgrade to the new 5000 series CPU, specifically a 5900 or 5950x so that entails getting the CPU and a new motherboard. That is not the issue.

So now that I've laid out my current build and what I'm wanting to upgrade to A few weeks ago I purchased 3 Sabrent gen4 m.2

2tb gen 4
1tb gen 4
500gig gen 4

Now, the issue here unless i'm mistaken, and I may very well be or just not understood the new AMD 5000 cpu Lanes and how they work. They have 24 lanes where 4 are allocated to the chipset, 1 for the GPU (I also plan on getting the 6900XT) which would leave 4 lanes left for 1 M.2 to run at full speed.

The issue here would my other 2 gen 4 m.2 upon installing still get gen4 speeds as from my understanding they seem to be taken up by the chipset, GPU and one of the m.2s.

Can someone please shed some light here and let me know if I would lose any gen4 speed on the other m.2s i plan on installing?

If I won't get full gen 4.0 speed I was just thinking of going for the 3950x has his from my understanding has 40 lanes which would be enough to drive a GPU and 3 m.2 gen 4 drives.

Thanks for info and answers you can provide.

 

[Sleepy Stu]

https://hexus.net/media/uploaded/2019/6/a2448e12-39d5-4552-912c-d33135455c00.png

**Do Not Hotlink Images **

 

[pc-guy]

you need x570 boards with upto 3 slots of PCIe x16 slots

the top 2 will be linked to CPU with PCIe 4.0 standard and they can be bifuricated to run x8/x4x4 and you need a PCIEx16 to M.2 card to get that working either in the top slot or middle slot. this will render the other x16 slot to pcie4x8 bandwidth so will limit your GPU output.

the two m.2 slots on motherboard are both PCIe4; one is connected to CPU and the other is via chipset.

so techinically you can have upto 4 pcie4 m.2 and you also got an additional option to populate the last PCIex16 slot as M.2 via adaptor but @ PCIe3 standard - this slot usually has shared resources with SATA ports so you will loose some SATA connections.

these board are not cheap BTW usually starts at £300

by using an APU (cpu with graphics) you will not save any PCIe lanes as the APU will automatically take up x16 lanes so you loose out on the top two slots and render to only motherboard M.2 PCIe 4 slots.

this question should be in the motherboard section.

 

[humbug]

I feel your pain, The problem is Motherboartd vendors are free to arrange the IO how they like, so i just looked at a couple of motherboards and the descriptions of the M.2 slots are either none existent or impossible to understand. Some just say "3X M.2" Well.... okay, so what type are they?
I was looking for something like, for example:

M.2 A: PCIe4
M.2 B: PCIe4
M.2 C: PCIe3

But no, that would mean people could actually work out what they are getting, and we can't have that....

 

[Sleepy Stu]

Ignore

 

[tamzzy]

If I won't get full gen 4.0 speed I was just thinking of going for the 3950x has his from my understanding has 40 lanes which would be enough to drive a GPU and 3 m.2 gen 4 drives.

All ryzen inc 3950x have 24 lanes (16 to gpu, 4 to 1st nvme, 4 to chipset)
40 Lane pcie is threadripper

Why do you require 3x pcie 4 drives?

 

[humbug]

Ignore

Then you look in the technical specifications and it says "2x M.2 slots (M2_2/ M2_3, Key M)"

One of the M.2 slots on my board is Sata.

What does "Triple Lighting" even mean?

 

[Sleepy Stu]

Then you look in the technical specifications and it says "2x M.2 slots (M2_2/ M2_3, Key M)"

One of the M.2 slots on my board is Sata.

What does "Triple Lighting" even mean?

Yep saw that after posting which is why I deleted my post!

 

[Mozauk]

All ryzen inc 3950x have 24 lanes (16 to gpu, 4 to 1st nvme, 4 to chipset)
40 Lane pcie is threadripper

Why do you require 3x pcie 4 drives?

Hello and thanks for replying.

Because I want to add 3 gen 4 m.2s and a 6900xt I was concerned whether I would loose any speed on the GPU or the 3 M.2s. Basically what I'm asking would my 3 m.2s gen4 and GPU loose speed or be hampered in anyway like lanes dropping down. Sorry if I'm not making sense or I'm misunderstanding how this all works.

 

[Mozauk]

All ryzen inc 3950x have 24 lanes (16 to gpu, 4 to 1st nvme, 4 to chipset)
40 Lane pcie is threadripper

Why do you require 3x pcie 4 drives?

1. for the system drive 500gig
2. for my games drive 2tb
3. for my graphic design, ms office etc software 1tb

 

[Sleepy Stu]

Hello and thanks for replying.

Because I want to add 3 gen 4 m.2s and a 6900xt I was concerned whether I would loose any speed on the GPU or the 3 M.2s. Basically what I'm asking would my 3 m.2s gen4 and GPU loose speed or be hampered in anyway like lanes dropping down. Sorry if I'm not making sense or I'm misunderstanding how this all works.

Ok so something like this

https://www.overclockers.co.uk/giga...4-x570-chipset-atx-motherboard-mb-57u-gi.html

Description lists

Triple Ultra-Fast NVMe PCIe 4.0/3.0 x4 M.2 with Triple Thermal Guards

Have looked about online would appear that the top slots, M2A and M2B, do not share any lanes with other devices. However, M2C (bottom slot) will disable SATA ports 4 and 5 when using a PCIe drive.

 

[VincentHanna]

I would personally stick to 2x Nvme drives and get a fast SATA SSD drive

 

[humbug]

Yep saw that after posting which is why I deleted my post!

Tricky, isn't it?

@Mozauk I think the most you will get is 2 PCIe4 M.2 slots, the speed of them should be effected as one comes from the Chipset and the other from the CPU, i haven't seen any caveats listed where you drop multiplication, only with the GPU if you run more than one, IE 1X PXIe4 X16 or 2X PCIe4 X8, that's because the GPU takes its PCIe lanes from the CPU which only has 16 available for the GPU, the CPU and Chipset are 4 lanes each for the M.2.

 

[humbug]

Ok so something like this

https://www.overclockers.co.uk/giga...4-x570-chipset-atx-motherboard-mb-57u-gi.html

Description lists

Triple Ultra-Fast NVMe PCIe 4.0/3.0 x4 M.2 with Triple Thermal Guards

Have looked about online would appear that the top slots, M2A and M2B, do not share any lanes with other devices. However, M2C (bottom slot) will disable SATA ports 4 and 5 when using a PCIe drive.

You maybe be on to something but ignore the marketing and see if you can work out from this what you're actually getting

Slots: Integrated in the CPU (PCIEX16/PCIEX8):3rd Generation AMD Ryzen™ processors:1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x16 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x8 (PCIEX8) 2nd Generation AMD Ryzen™ processors:1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x16 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX8) For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot. The PCIEX8 slot shares bandwidth with the PCIEX16 slot. When using the 3rd Generation AMD Ryzen™ processors/2nd Generation AMD Ryzen™ processors, the PCIEX16 slot operates at up to x8 mode. 2nd Generation AMD Ryzen™ with Radeon™ Vega Graphics processors/AMD Ryzen™ with Radeon™ Vega Graphics processors:1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX8) Integrated in the Chipset (PCIEX4):1 x PCI Express x16 slot, supporting PCIe 4.0*/3.0 and running at x4 For 3rd Generation AMD Ryzen™ processors only.2 x PCI Express x1 slots, supporting PCIe 4.0*/3.0 For 3rd Generation AMD Ryzen™ processors only.

 

[Vince]

All ryzen inc 3950x have 24 lanes (16 to gpu, 4 to 1st nvme, 4 to chipset)
40 Lane pcie is threadripper

Why do you require 3x pcie 4 drives?

3 is not nearly enough - People that require this are not requiring it for gaming that much I am sure of I for example currently have 7x m.2 in my machine.

 

[Sleepy Stu]

Yeah its crap to read isn't it a little bit of formatting wouldn't go amiss!! If we split it up it would read like this I guess? The line in bold makes no sense though?


Slots: Integrated in the CPU (PCIEX16/PCIEX8):

3rd Generation AMD Ryzen™ processors:1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x16 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x8 (PCIEX8)

2nd Generation AMD Ryzen™ processors:1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x16 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX8)

For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot. The PCIEX8 slot shares bandwidth with the PCIEX16 slot.

When using the 3rd Generation AMD Ryzen™ processors/2nd Generation AMD Ryzen™ processors, the PCIEX16 slot operates at up to x8 mode.

2nd Generation AMD Ryzen™ with Radeon™ Vega Graphics processors/AMD Ryzen™ with Radeon™ Vega Graphics processors:1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX8) Integrated in the Chipset (PCIEX4):1 x PCI Express x16 slot, supporting PCIe 4.0*/3.0 and running at x4 For 3rd Generation AMD Ryzen™ processors only.2 x PCI Express x1 slots, supporting PCIe 4.0*/3.0 For 3rd Generation AMD Ryzen™ processors only.

 

[tamzzy]

1. for the system drive 500gig
2. for my games drive 2tb
3. for my graphic design, ms office etc software 1tb

Just combine and have 2x 2tb drives perhaps? Not really needing a separate system and games drive unless you're doing weekly windows reformats?

3 is not nearly enough - People that require this are not requiring it for gaming that much I am sure of I for example currently have 7x m.2 in my machine.

True, but I suspect op doesn't really require 3 nvme drives from what he's describing.

 

[humbug]

3 is not nearly enough - People that require this are not requiring it for gaming that much I am sure of I for example currently have 7x m.2 in my machine.

You're just greedy

Yeah its crap to read isn't it a little bit of formatting wouldn't go amiss!! If we split it up it would read like this I guess? The line in bold makes no sense though?


Slots: Integrated in the CPU (PCIEX16/PCIEX8):

3rd Generation AMD Ryzen™ processors:1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x16 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 4.0 and running at x8 (PCIEX8)

2nd Generation AMD Ryzen™ processors:1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x16 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX8)

For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot. The PCIEX8 slot shares bandwidth with the PCIEX16 slot.

When using the 3rd Generation AMD Ryzen™ processors/2nd Generation AMD Ryzen™ processors, the PCIEX16 slot operates at up to x8 mode.

2nd Generation AMD Ryzen™ with Radeon™ Vega Graphics processors/AMD Ryzen™ with Radeon™ Vega Graphics processors:1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX16)1 x PCI Express x16 slot, supporting PCIe 3.0 and running at x8 (PCIEX8) Integrated in the Chipset (PCIEX4):1 x PCI Express x16 slot, supporting PCIe 4.0*/3.0 and running at x4 For 3rd Generation AMD Ryzen™ processors only.2 x PCI Express x1 slots, supporting PCIe 4.0*/3.0 For 3rd Generation AMD Ryzen™ processors only.

I quoted the wrong paragraph.

Storage:
Integrated in the CPU (M2A_SOCKET): 3rd Generation AMD Ryzen™ processors:1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 4.0 x4/x2 SSD support) 2nd Generation AMD Ryzen™ processors/2nd Generation AMD Ryzen™ with Radeon™ Vega Graphics processors/AMD Ryzen™ with Radeon™ Vega Graphics processors: 1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 3.0 x4/x2 SSD support) Integrated in the Chipset (M2B_SOCKET/M2C_SOCKET):Integrated in the CPU (M2A_SOCKET):3rd Generation AMD Ryzen™ processors:1 x M.2 connector Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 4.0 x4/x2 SSD support 2nd Generation AMD Ryzen™ processors/2nd Generation AMD Ryzen™ with Radeon™ Vega Graphics processors/AMD Ryzen™ with Radeon™ Vega Graphics processors:1 x M.2 connector Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 3.0 x4/x2 SSD support Integrated in the Chipset (M2B_SOCKET):1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 4.0/3.0 x4/x2 SSD support) For 3rd Generation AMD Ryzen™ processors only) 6 x SATA 6Gb/s connectors Support for RAID 0, RAID 1, and RAID 10

There are 3 M.2 slots on that board and only once is the third mentioned...

1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 3.0 x4/x2 SSD support) Integrated in the Chipset (M2B_SOCKET/M2C_SOCKET)

What? is that (PCIe4 / SSD X2) IE Socket (M2B = PCIe4 / M2C = SSD) IE Sata ????? M2C is Sata, Not PCIe4.

 

[tamzzy]

Hello and thanks for replying.

Because I want to add 3 gen 4 m.2s and a 6900xt I was concerned whether I would loose any speed on the GPU or the 3 M.2s. Basically what I'm asking would my 3 m.2s gen4 and GPU loose speed or be hampered in anyway like lanes dropping down. Sorry if I'm not making sense or I'm misunderstanding how this all works.

Your gpu will run at x16
Your 1st nvme drive will run at full x4
Your second and third nvme drive speeds will vary depending on what the chipset is configured as. But it won't run at full pcie 4.0 x4 speeds if both are being hammered at the same time as the chipset uplink is pcie 4.0 x4 (can't magic out an extra 4 lanes out of nowhere)

 

[Vince]

You're just greedy .

... you got me, this is my current pile of nvme that I have no idea what to do with



Perhaps the op also has 50 nvme drives and no idea what to do with them?!