MSI MAG Tomahawk Z490 - Am I understanding the PCIE lane distribution and it's affects on SATA availability?

xMAGIUSx

n00b
Joined
Oct 8, 2020
Messages
57
I am building a new PC for the first time since 2012 and want to make sure I'm understanding things before assembly.

The motherboard is an MSI MAG Tomahawk Z490, the processor is a 10700K

I want to run NVMe M.2 hard drives in both M.2 slots. From what I can see in the motherboard manual this will disable SATA ports 2, 5 & 6 - which I am ok with. It does not appear that populating both M.2 slots will reduce available bandwidth of the PCIe 3.0 x16 slot. Is that accurate?

If I were to then populate one or both of the PCIe x1 slots, would they steal bandwidth from anywhere else? From the flow chart below (third image) it seems they do not, but bandwidth splitting is a new concept to me. Is it even really a concern if I only play to run a single GPU?

I've included screen grabs of all relevant sections from the motherboard manual.

Any insight would be greatly appreciated. Thanks for your time.

image1.jpg



image2.jpg


image3.jpg
image4.jpg
image5.jpg
 

E4g1e

Supreme [H]ardness
Joined
May 21, 2002
Messages
7,225
If both of your m.2 SSDs are NVMe, then they are (by extension) both PCIe SSDs. SATA does not support the NVMe protocol. Therefore, with your motherboard only SATA5 amd SATA6 are disabled (as noted under the column where both the M2_1 and M2_2 slots are filled with PCIe SSDs). It's only when the M2_1 slot is occupied with an m.2 SATA SSD that the SATA2 port is disabled.
 

xMAGIUSx

n00b
Joined
Oct 8, 2020
Messages
57
If both of your m.2 SSDs are NVMe, then they are (by extension) both PCIe SSDs. SATA does not support the NVMe protocol. Therefore, with your motherboard only SATA5 amd SATA6 are disabled (as noted under the column where both the M2_1 and M2_2 slots are filled with PCIe SSDs). It's only when the M2_1 slot is occupied with an m.2 SATA SSD that the SATA2 port is disabled.
Thank you for the clarification. I used to be pretty on top of things hardware wise but I have a lot of catching up to do.

I wasn’t too worried about the loss of SATA ports as I don’t plan to run any drives besides the NVMe drives right now. It’s nice to know that I’ll only lose two SATA ports though, which are the vertical ones I wouldn’t have used anyway.
 

Dan_D

Extremely [H]
Joined
Feb 9, 2002
Messages
57,022
You understand correctly. The M.2 slots get their lanes from the PCH. The GPU goes direct to the CPU.
 

xMAGIUSx

n00b
Joined
Oct 8, 2020
Messages
57
You understand correctly. The M.2 slots get their lanes from the PCH. The GPU goes direct to the CPU.
Thank you.

I only plan to run a single GPU, but would populating the PCIe 3.0 x4 slot, or the PCIe x1 slots result in removing available bandwidth to either the gpu or NVMe drives?

Since nothing was mentioned in the motherboard manual, I think the answer is no, but I want to be sure. PCIe 3.0 was new and PCIe based hard drives did not exist the last time I built a machine.
 
Top