why are there 3 PCIe 3.0 x16 slots on a z97 msi gaming mobo ?

[Mohamed El Moheb]

It might sound like a noob question but z97 cpus only have a maximum of 16 pcie lanes, so technically speaking, you can only install one gpu and have it run at x16. If I want to put 2 gpus in sli, then they would run each at x8. So isnt it useless to have 3 slots of x16 ? You cant run 3 gpus at x16 on a z97 mobo. So why did they put 3 x16 slots ?

 

[beshonk]

They run at x8 x4 x4 and while you could technically run 3 cards like that (might not even be supported by motherboard) you'd be much better off with x58 and 2 cards at that point.

 

[Mohamed El Moheb]

They run at x8 x4 x4 and while you could technically run 3 cards like that (might not even be supported by motherboard) you'd be much better off with x58 and 2 cards at that point.

when they say that the z97 cpus have 16 pcie lanes, do they mean that for the 3.0 PCIe lanes ? In other words, do these cpus have additional lanes for 2.0 PCIe slots? Can I run 2 GPUs at x8 x8 at 3.0, and have simultaneously a soundcard running at PCIe 2.0 x1 with a cpu that has 16 PCIe lanes ?

 

[endeavour37a]

That's true for Nvidia cards, they need 8 lanes each, AMD cards will run on 4 lanes in XFire.....

 

[stormflakes]

hey,

nvidea doesnt work with x4, but amd does.
What you can do as well is install an ssd in an m2.0 slot if the board supports it.

But like you said, it's a bit stupid cause no sane person will run 3 gpu's in that board.

2x gpu and one ssd is already stupid soooo. PR maybe?

 

[beshonk]

PCIE 2.0 and any legacy pci lanes are built into the northbridge on z97. So you get full 16 lanes for the pcie3.0 slots from the cpu, and the rest of the pcie connectivity is handled by the motherboard.

 

[Mohamed El Moheb]

hey,

nvidea doesnt work with x4, but amd does.
What you can do as well is install an ssd in an m2.0 slot if the board supports it.

But like you said, it's a bit stupid cause no sane person will run 3 gpu's in that board.

2x gpu and one ssd is already stupid soooo. PR maybe?

so I can run 2 gpus at 8x and still run a m.2 ssd card and a 2.0 PCIe 1x sound card ?

 

[Mohamed El Moheb]

PCIE 2.0 and any legacy pci lanes are built into the northbridge on z97. So you get full 16 lanes for the pcie3.0 slots from the cpu, and the rest of the pcie connectivity is handled by the motherboard.

I didnt understand. so the other PCIe 3.0 16x are handled by the motherboard ? so i can run 16x PCIe 3.0 gpus ?

 

[stormflakes]

there are 4 options:

16x0x0 : for 1x GPU
8x4x4: for 1 gpu and an ssd in an M2.0 slot ( mostly third slot )
8x8x0: for 2x GPU
8x4x4: for 2x GPU + 1SSD ( only for AMD because nvidea doenst support 4x )

so the board is very good for 2xGPU, and 1xGPU and 1ssd ( but it's better to stick the ssd in the sata express )

for this ( and all other mid-end boards ) you got 16 lanes. You must devide them over 1,2 or 3 slots.
the only possibilities are:
16x0x0; 8x8x0; 8x4x4

hope that makes it clear

 

[beshonk]

What I'm saying is, PCIE 3.0 had 16 lanes handled by the CPU. All other PCIE 2.0 lanes are built into the motherboard, so anything you put into a PCIE slot that is not the 3.0 slots will be handled by the motherboard. (for instance, that sound card, will not consume your pcie 3.0 lanes).

 

[Mohamed El Moheb]

What I'm saying is, PCIE 3.0 had 16 lanes handled by the CPU. All other PCIE 2.0 lanes are built into the motherboard, so anything you put into a PCIE slot that is not the 3.0 slots will be handled by the motherboard. (for instance, that sound card, will not consume your pcie 3.0 lanes).

This is exactly the answer I was looking for ! And the number of PCIe 2.0 lanes depends on the motherboard or do all the motherboards have the same number of PCIe 2.0 lanes ?

 

[beshonk]

I am not sure if they differ by motherboard. Since they're all Z97 chipset, i assume that it's the same number for every motherboard with that chipset. That would make sense since it's handled by the northbridge which is chipset specific, not mobo specific.