PCI Lanes

[FuegoFett]

I recently purchased an Intel I9-9900k and an MSI MEG Z390 ACE with an MSI Geforce RTX 2080 Gaming X Trio and a Samsung 970 Pro m.2 512gb X4. My question is whether or not The PCI lanes will diminish from the m.2 or if it will use the lanes from the chipset. And if it is the chipset.... How many lanes does it provide in case I wanted to use the other 2 m.2 slots.

[mariushm]

It will say in the motherboard manual. Download the manual from MSI's website and browse through it and you'll find out.

 

[FuegoFett]

I have tried that already. It is not listed unfortunately. I have attached their manual pdf. 

7B12v1.0(G52-7B121X1)(MEG Z390 ACE).pdf

[Sakkura]

The M.2 slots are all connected via the chipset. As the connection between the chipset and CPU can only transfer just under 4 GB/s, that's the maximum combined speed you'd be able to get out of multiple M.2 SSDs on that board. It can also be less than that as other things connect via the chipset as well (SATA drives, networking, USB etc).

[FuegoFett]

1 minute ago, Sakkura said:

The M.2 slots are all connected via the chipset. As the connection between the chipset and CPU can only transfer just under 4 GB/s, that's the maximum combined speed you'd be able to get out of multiple M.2 SSDs on that board. It can also be less than that as other things connect via the chipset as well (SATA drives, networking, USB etc).

Thanks. So I should get all X4 m.2 or with multiplle, would it be better to run OS off an X4 and the other 2 on x1?

[Sakkura]

1 minute ago, FuegoFett said:

Thanks. So I should get all X4 m.2 or with multiplle, would it be better to run OS off an X4 and the other 2 on x1?

Depends what you'll be using the system for. Most normal uses wouldn't include multiple SSDs transferring 2-3+ GB/s of data simultaneously, so the chipset bottleneck wouldn't be worth worrying about.

[mariushm]

See http://download.msi.com/archive/mnu_exe/M7B12v1.0_EURO.zip

 

Page 4 (14 of 288)

 

3x PCIe 3.0 x16 slots,
. Support x16/ x0/ x0, x8/ x8/ x0, x8/ x4/ x4 modes
3x PCIe 3.0 x1 slots

 

so the pci-e x16 slots are from the CPU... 16 lanes are split between the 3 slots as needed.

one graphics card : pci-e x16 , disabled, disabled

two graphic cards : pci-e x8, x8 , disabled

3 devices : x8, x4, x4

 

Look under Storage ... see the first line Intel Z390 chipset ? That tells you all M.2 connectors listed there are connected to chipset.

See the * which points you to fineprint - if you use the M.2 slot, they share bandwidth with SATA ports so some SATA ports become disabled. See page 21 which says

See page 18 : overview of pci-e expansion slots :

 

 

 

page 21 tells you which sata ports become disabled when you use m.2 devices that use SATA protocol to communicate. Also SATA5 and SATA6 are disabled with m.2 nvme on m2_2 connector due to lack of pci-e lanes (well, HSIO lanes but same shit) created by chipset:

 

 

 

 

 

 

[FuegoFett]

Just now, Sakkura said:

Depends what you'll be using the system for. Most normal uses wouldn't include multiple SSDs transferring 2-3+ GB/s of data simultaneously, so the chipset bottleneck wouldn't be worth worrying about.

Gaming, scripting, network security and streaming.