ASUS Z170i with M.2

Tephnos · 18 Oct 2016 at 18:40

Hard to find confirmation on this. Does using an M.2 drive with the Asus Pro gaming z170i drop GPU bandwidth down to x8 or not?

On a video from EDGE UP it claims to do so, but I'd like for someone who owns the board to actually confirm this because it would be really stupid pulling from GPU lanes when you don't need to with Skylake.

pastymuncher · 18 Oct 2016 at 18:48

None of the reviews that I have just checked mention it and neither does Asus website. I really can't see why it would anyway as it only has a single pci-e 3.0 16x slot so there is loads of extra pci-e lanes left over. I think the site you saw it on were mistaken.

Tephnos · 18 Oct 2016 at 18:57

pastymuncher said:
None of the reviews that I have just checked mention it and neither does Asus website. I really can't see why it would anyway as it only has a single pci-e 3.0 16x slot so there is loads of extra pci-e lanes left over. I think the site you saw it on were mistaken.

This was the video specifically. (Around 12:30+)

Seems like he's wrong though, so thank god for that.

pastymuncher · 19 Oct 2016 at 09:57

Either he is wrong or every other review plus Asus own website is wrong as well. I can't see why he would think that the only pci-e 16x slot would drop to 8x with a M2 drive installed. There are loads of spare lanes left over. Doing some more investigation it would seem that the M2 slot takes it lanes from the Z170 chipset as well meaning it shouldn't affect the pci-e slot as that is supplied from the lanes from the cpu.

Smffy · 19 Oct 2016 at 21:30

Pretty sure the dedicated SATA bandwidth for the slots is a feature of the Z170 chipset... Designed for that very reason.

I did find a Tomshardware post which had a really clear explanation of it but can't find it now. Anyway I can confirm that I've got one and no it doesn't eat the GPU speed as long as you use the dedicated slot in the motherboard (i.e. the horizontal mount on the board) and not the PCI-E M.2 slot adapter in the box.

I've got a Z170 Deluxe, 6700k.

Edit:

"Z170 motherboards have 16 PCIe 3.0 lanes running between the CPU and the PCIe slots.

Then there are 26 additional PCIe 3.0 lanes coming from the Z170 chipset which are intended for add ons... SATA III, SATA Express, USB, M.2 x4, and so on. That is what the colorful chart above shows. Some are predefined as to what Intel wants them to be used for, but most can be easily reassigned by a motherboard designer."