M.2 - does it take up CPU PCIe lanes or not?

[arye88]

Hey all.

I'll start by saying that I did search a little before posting, but got mixed answers so I decided I'll ask here before I buy.

Looking to build a SFF PC. I saw MSI has a low profile GTX 1050 Ti, so I thought I'll buy and use it.

Point is, I wanna buy a M.2 stick for OS and programs storage, but I do not know if it uses 4 of the 16 CPU PCIe lanes.

Some say the M.2 is connected directly to the chipest and does not use any CPU lanes, if so - doesn't it make the M.2 as a regular SSD?

And if it does use the CPU lanes, will it affect my graphics card performance much?

How do I weigh between the two, what will yeild me better results, using SSD through SATA and running my GPU at 16x, or connecting the CPU directly to the M.2 storage device but cutting in half the speed at which my GPU runs?

Will use this system mostly for CAD work (autocad) and some gaming.

This is the MOBO: https://www.asus.com/Motherboards/PRIME-Z270M-PLUS/
This is the graphics cards: https://www.msi.com/Graphics-card/GeForce-GTX-1050-Ti-4GT-LP.html#hero-overview

Thanks everyone for any assistance, and forgive me for the long answer.

 

[Barty1884]

No, the a PCIe/NVME SSD uses the x4 provided via the chipset.

A consumer CPU provides a max 16 lanes, utilized in the x16 slot by your GPU (or as SLI two x8s)
The H100 series, Z170 and B150 had an extra 4 PCIe lanes (for max 20 when added to the CPU).

The 200 series is max 24, so brings an extra 8 to the table. You can use 2x M.2 NVME SSDs (both x4) and still have the full x16 available to your GPU.

 

[kraelic]

It would depend on the maker to be honest. Some might use lanes from the CPU, most use the lanes from the south bridge.

If you have an x99 for instance and a 28 lane CPU, you can have a x16/x8/x4 slot configuration where the first two can use SLI, and the x4 can use the intel 750 ssd, or m.2 to pci-e adapters.

I think there are a few x99 that have the onboard m.2 tied into the CPU like http://techreport.com/review/26973/asus-x99-deluxe-motherboard-reviewed.

Most Z boards are tied into the southbridge. Z170 has 20 lanes not including the CPU, and Z270 has 24 lanes. both use max of 3 x4 m.2 and the rest of the lanes go to other items, gigabit LAN, USB-C, any x1 slots, etc.

https://linustechtips.com/main/topic/424724-z170-not-enough-pcie-lanes/?do=findComment&comment=5701211
Link to the Z170 block diagram, x16 to cpu, up to x20 to chipset, DMI link between CPU and chipset. B and H have reduced lanes.

 

[arye88]

I thank you both for all the assistance, Barty1884 and kraelic.
If anyone else has anything more to suggest/reply regarding the matter, please do so.
Thanks once more :]