Few PCIe lanes on home motherboards for how long?

[Nhonho]

The (brand new) TUF GAMING X870-PLUS WIFI motherboard has 4 slots for M.2 SSDs, but if an SSD is placed in the M.2_2 slot, the main PCIe 16x slot will operate with only 8 PCIe lanes. And if the person places an SSD in the M.2_4 slot, the second PCIe 16x slot (with 4 PCIe lanes) will simply be disabled.

It is very likely that many people who are going to buy this motherboard will go through some serious "headaches" until they realize that they cannot occupy all the slots at the same time.

People are using more and more M.2 SSDs, and, therefore, AMD has to make more PCIe lanes available in its CPUs and chipsets.

See page 8:

https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM5/TUF_GAMING_X870-PLUS_WIFI/E24080_TUF_GAMING_X870-PLUS_WIFI_EM_WEB.pdf?model=TUF%20GAMING%20X870-PLUS%20WIFI

 

[ir_cow]

Nothing new going on here. Consumer product lines from Intel and AMD have been this way for a number of generations now.

 

[DaemonForce]

Yeah I ran into similar on X570 but didn't get the option to set PCI-E lane usage for top slot until a very late BIOS update.
I can occupy the top M.2 slot, given.
I can occupy 16 lanes in top PCI-E slot.
I can even plug whatever into the bottom X16 slot and bottom M.2, no problem.
But when I plug ANYTHING into either of the X1 slots, bottom X16 and M.2 disabled.
Can't have it all unless I go back to AM3+ and it's all Gen 2. No idea if my M.2 adapter works there.
I won't buy any more boards until we get more PCI-E lanes or I run into another multi-PC project where it's fine.

Nothing new going on here. Consumer product lines from Intel and AMD have been this way for a number of generations now.

Intel has been ahead of things with their recent boards though. Their PCI-E arrangements make actual real world sense.
Maybe I don't like closed X1 slots. Maybe littering with a few open/X2 slots are the stopgap answer until we get more lanes.

 

[ir_cow]

I'm running PCIe 8x right now. Not a big deal.

 

[JWNoctis]

One more reason to give the datasheet a read, and avoid those boards if it does not fit your use, before buying anything.

20 to 24 lanes of CPU-derived PCIe 4.0/5.0 buses are enough for most home use, where most people won't populate more than the PEG slot and one M.2 slot. For those who does need more, though...The days of high-lane-count SLI/CrossFire CPUs, NBs, and boards are long gone.

 

[Nhonho]

Nothing new going on here. Consumer product lines from Intel and AMD have been this way for a number of generations now.

So it's time for a change, right?

Motherboards should be as "plug and play" as possible. This issue of having to study the PCIe lines of a motherboard should not even exist. This is a step backwards in the evolution and simplification of the PC.

datasheet

Page 8:

https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM5/TUF_GAMING_X870-PLUS_WIFI/E24080_TUF_GAMING_X870-PLUS_WIFI_EM_WEB.pdf?model=TUF%20GAMING%20X870-PLUS%20WIFI

 

[stahlhart]

I made use of the Hyper m.2 card that came with my Asus board, and was able to avoid needing to use that virtually worthless PCIe 5.0 slot, along with its completely worthless heat sink. Not only the issue of it stealing lanes from the GPU when used, but also the unfortunate drive mounted there ending up getting cooked by it.

 

[Asni]

You are going to realize that the amount of pci-ex lanes isn't important anymore, we should talk about bandwidth, when gpu manufacturers are going to base their whole lineup on x8 interfaces (i'm expecting anything below 5080 on x8 interface, gen5 obv).

You really don't need more than 104GB/s of usable bandwidth (24xgen5+4xgen4).

 

[cal5582]

Nothing new going on here. Consumer product lines from Intel and AMD have been this way for a number of generations now.

idk man i didnt have these issues with am4 and the x570 motherboards. plenty of slots on those. x670e was pretty much a downgrade for me. ram compatibility was worse going to ddr5 (cant use all 4 sticks at full speeds didnt have those issues with ddr4), number of pcie slots was cut down to make room for m.2 slots (why so many dedicated m.2 slots when you can use a pcie adapter and have 4+ m.2 drives on one card) etc

 

[SL2]

why so many dedicated m.2 slots when you can use a pcie adapter and have 4+ m.2 drives on one card

I'd guess more SSD lots is much more in demand than PCIE slots besides graphics.

In general.

 

[windwhirl]

People are using more and more M.2 SSDs, and, therefore, AMD has to make more PCIe lanes available in its CPUs and chipsets.

To be honest, I don't think many people use that many M2 SSDs simultaneously.

Plus, AMD or whoever would probably tell you to get a X870E board, not a vanilla X870 board, since X870E has more PCIE lanes.

You also have SATA ports. SATA SSDs do a fine job too. You can use those.

I'd guess more SSD lots is much more in demand than PCIE slots besides graphics.

In general.

Most of what people would plug in a PCI slot was onboarded after all, so they just feed off PCIE lanes internally.

 

[Wirko]

Most of what people would plug in a PCI slot was onboarded after all

Either onboarded or made external. The choice of available USB peripherals is vast and it's growing, and each of them is usable on multiple PCs if necessary.

 

[Arco]

To be honest, I don't think many people use that many M2 SSDs simultaneously.

Not many, but these are meant to be top of the line boards and they only support 2-3 before dropping to x8 on the main slot. I use 3 M.2s as of the moment but I used to use 4.

 

[dirtyferret]

Nothing new going on here. Consumer product lines from Intel and AMD have been this way for a number of generations now.

OP was today years old when he found out you need to read the mobo manual on how PCEi expansion slot layout works

 

[windwhirl]

OP was today years old when he found out you need to read the mobo manual on how PCEi expansion slot layout works

To be fair, anyone could think that if a board has 4 M2 slots, all 4 are usable under any condition.

On the other hand, you might not even need to read the manual, as the specs page would tell you about that as well

 

[Nhonho]

To be fair, anyone could think that if a board has 4 M2 slots, all 4 are usable under any condition.

That's it.

This thing about disabling lines or slots should stop. It's a strange, bizarre thing.

As I said in post #6, motherboards should be as "plug and play" as possible. This issue of having to study the PCIe lines of a motherboard should not even exist. This is a step backwards in the evolution and simplification of the PC.

 

[dirtyferret]

This is a step backwards in the evolution and simplification of the PC.

how can it be a step backwards if it's been this way for generations. I understand you are upset because you failed to know this fact but that line would intend the previous generation did have more PCIe lanes. There is a manufacturing cost to both the CPU and mobo to make this work and if it really bothers you so much just get a HEDT workstation.

To be fair, anyone could think that if a board has 4 M2 slots, all 4 are usable under any condition.

anyone can think a threadripper CPU is a better gaming CPU than the 9900X3D because it has more cores, caveat emptor when there is no research done

 

[Nhonho]

Maybe littering with a few open/X2 slots are the stopgap answer until we get more lanes.

Yes, instead of disabling AIC (add in cards) slot lines, they should keep all AIC slot lines and disable two lines of some M.2 slots only.

 

[cal5582]

That's it.

This thing about disabling lines or slots should stop. It's a strange, bizarre thing.

As I said in post #6, motherboards should be as "plug and play" as possible. This issue of having to study the PCIe lines of a motherboard should not even exist. This is a step backwards in the evolution and simplification of the PC.

yeah thats my complaint. you can buy an adapter to turn a pcie slot into multiple m.2 devices.
m.2 to pcie adapters never reach to actually screw the card into the slot. kind of a PITA if god forbid you need to actually use more than one device.

 

[DirtyDingusMcgee]

Why sure. Let's just convince AMD and Intel to make every cpu have as many pci-e lanes as an eypc/xeon, the clocks of high end R9/i9, and a 16 gig 3d cache.

Is this really an issue for those who know what they are getting before they buy it?

 

[cal5582]

Why sure. Let's just convince AMD and Intel to make every cpu have as many pci-e lanes as an eypc/xeon, the clocks of high end R9/i9, and a 16 gig 3d cache.

Is this really an issue for those who know what they are getting before they buy it?

i mean id argue the x570 had some good high end boards with plenty of pcie slots. youd think buying an x670e board at the same price range youd be getting at least the same amount of extensibility not less. i wouldnt complain if there was any sort of high end option above that. id even settle for a non-pro threadripper available to non-oems if they werent close to 1 generation behind at launch.

 

[Dorek]

Guess my mobo had a bit better options, not sure.

 

[GerKNG]

The (brand new) TUF GAMING X870-PLUS WIFI motherboard has 4 slots for M.2 SSDs, but if an SSD is placed in the M.2_2 slot, the main PCIe 16x slot will operate with only 8 PCIe lanes. And if the person places an SSD in the M.2_4 slot, the second PCIe 16x slot (with 4 PCIe lanes) will simply be disabled.

because you probably specifically looked for a board that has two M.2 Gen 5 Slots which are not supported by the CPUs NVMe PCIe lane layout.
you can run 4 NVMe SSDs without any issues and this is normal if motherboard manufacturers would actually build a board with the spec in mind instead of making a second gen 5 slot that must use your CPU provided GPU lanes with a switch.

X870 Aorus Elite for example:

 

[Dr. Dro]

The X670E/X870E motherboards help mitigate this a bit over regular X670/X870, B650E also being a good option. All in all, PCIe lanes are a commodity in modern consumer-grade desktops (including Intel platforms), and you should plan ahead and use these resources wisely.

 

[DaemonForce]

the amount of pci-ex lanes isn't important anymore, we should talk about bandwidth

Until we get better product all around, these qualities aren't really divorceable.
I can dump a full size G3X16 card into a slot only pinned G4X4 and it will run fine at G3X4.
I can't run everything I want when the existence of a component in one particular slot disables half the board.
That is stupid design and you already know what we do with stupid designs.
I may not need even half the bandwidth of my equipment but the inability to bifurcate or otherwise properly distribute those lanes/bandwidth is the primary problem.
We're lucky that we have options in boards that don't have as much restrictive behavior but in the end we're still juggling lanes for whatever XYZ purpose.

For the majority of us running a single modern computer, we run a minimum single M.2 with options for dual or M.2 RAID.
We absolutely need a full size PCI-E slot just for the ability to provide lanes for whatever we find most important.
For most of us that's going to be a big honkin chonker of a GPU that displaces 2-4 slots.
The rest need advanced networking or storage that occupies two whole slots.
So the next PCI-E slot pinned X4, X8 or whatever makes sense to be at least that distance on full size boards.
Then there's typically an errant useless X1 slot pinned the furthest away. Why?
What purpose does this have when the main slots are full?
We need to get rid of that and start borrowing from older and SFF designs where an X1 slot is shared with top M.2 or something.