Need some advice regarding PCIe lanes?

[Space Monkey]

Hi guys,

I'm looking at getting an Aqua Computer M.2 PCIe 3.0 x4 adapter card for my Samsung 960 Pro M.2 NVMe SSD to use in my Asus Crosshair VI Extreme motherboard and I'm concerned that the only slot that will give the full PCIe 3.0 x4 bandwidth is shared with my GPU (GTX 1080).

(I'm using a Ryzen 7 1800X CPU)

Here is the relevant page from the Asus manual:






Here is the Aqua Computer adapter card:

https://www.overclockers.co.uk/aqua...sd-m-key-with-passive-heatsink-cc-000-aq.html

Here is the Samsung M.2 NVMe SSD:

https://www.overclockers.co.uk/sams...-3.0-x4-nvme-solid-state-drive-hd-22j-sa.html


So will I lose half the bandwidth to my GPU if I use the other PCIe 3.0 socket or is it only reduced if I use a 2nd GPU?

Will I loose a lot of bandwidth if the SSD had to go in a PCIe 2.0 lane?

 

[BongoHunter]

Is there a reason that your not using the M2 slot on the board for this drive?

 

[Space Monkey]

Is there a reason that your not using the M2 slot on the board for this drive?

Yeah sorry forgot to say, I'm interested in buying the water cooling block setup for the Aqua Computer adapter to integrate into my custom loop

 

[Marak]

Yes, your GPU will now only have 8x lanes to it if you use the other slot with the adaptor.

I wouldn’t worry too much though I do the same with an U2 adaptor for my intel 750 drive.

My 1080Ti loses about 1-2% performance from the 16x speed. With g-sync that makes it effectively unnoticeable.

 

[Habakkuk]

You shouldn't be able to saturate the interface, so the difference will be a rounding error.

 

[Space Monkey]

Thanks guys, that's good to know, think I'll chance it and get the adaptor

 

[Sasahara]

If you did notice a reduction in GPU performance just use the the PCIe x4 slot.

It is PCIe 2.0 so it would limited read/write speeds a bit, but it will still be probably faster than it need to be in most home usage. There aren't that many normal usage situations where you can process 3500Mb/s.


One of the reviews states they had 2200Mb/s read and 1550Mb/s write on 3.0 and 1400/Mb/s on 2.0 using the lower spec M2 SM951.

The biggest benefit of SSD/M2 drive it it the fast seek time/IOPS, you can still get all or most the benefit of that on the slower PCIe 2.0.

 

[nashathedog]

If you did notice a reduction in GPU performance just use the the PCIe x4 slot.

This.

I was using my M.2 with an adapter on my Z97 hero motherboard and it made no difference from what I could tell.

 

[Space Monkey]

Good idea, gives me another option, I'll likely use this as I'll probably not notice a slight drop in the NVMe speeds but I want all me frames with my 1080, especially considering how much frames cost these days