I'm in need of a new motherboard ... . confusion among lanes

[reaper7534!]

will I run into issues with the following for Z170x

One m.2 Samsung 950 Pro nvme drive
Two GTX 1070 SLI
One Samsung EVO SSD
One WD Black HDD

Will I get full speed on everything ?

I'm deciding between

GIGABYTE GA-Z170X-UD3 Ultra (rev. 1.0) LGA 1151 Intel Z170 HDMI SATA 6Gb/s USB 3.1 USB 3.0 ATX Motherboards - Intel - Newegg.com

and

GIGABYTE GA-Z170X-Designare (rev. 1.0) LGA 1151 Intel Z170 HDMI SATA 6Gb/s USB 3.1 USB 3.0 ATX Motherboards - Intel - Newegg.com

 

[lukart]

Another option would be:
ASRock Z170 Extreme4+ LGA 1151 Intel Z170 HDMI SATA 6Gb/s USB 3.1 USB 3.0 ATX Intel Motherboard - Newegg.com

 

[Bandalo]

The motherboard won't matter, the chipset + CPU really determine your available PCIe lanes. IIRC, the Z170 has 20 total PCIe lanes. So your first GPU will use 16, your second will use 16, and your 950 Pro will use 4...which is 40 total, twice what you have.

So what will happen is your MB will drop the video cards down to 8x / 8x, and your 950 Pro will still use 4x, giving you 20 total used. All your other PCIe slots can not be used. In most systems, you won't see any real difference between PCIe 3.0 at 8x vice 16x.

Your SATA SSD and HDD have dedicated lanes from the Z170 chipset, so they shouldn't be affected. Depending on the MB, it may have U2 or SataExpress ports that share lanes with the M.2 slots. So if you install the 950 Pro, those will be unavailable, but there should still be a few full-speed SATA3 ports available.

 

[L1amrob]

Like you Bandalo said, not much performance difference from 16x to 8x.
That Asrock Z170 Extreme looks good.