Asus X99-A/USB 3.1 Understanding PCIE

[UrbanFreestyle]

Hi all, I was hoping someone could help me decrypt this section of my user manual:

Spoiler

40-LANE CPU
3 x PCI Express 3.0/2.0 x16 slots* (single at x16, dual at x16/x16,
triple at x16/x16/x8)
1 x PCI Express 2.0 x16 slot*** (max. at x4 mode, compatible with
PCIe x1 and PCIe x4 devices
2 x PCI Express 2.0 x1 slot*** (compatible with PCIe x1 and x4
devices
28-LANE CPU
3 x PCI Express 3.0/2.0 x16 slots* (single at x16, dual at x16/x8**,
triple at x16/x8**/x4)
1 x PCI Express 2.0 x16 slot*** (max. at x4 mode, compatible with
PCIe x1 and x4 devices)
2 x PCI Express 2.0 x1 slot*** (compatible with PCIe x1 and x4
devices)
* The PCIe x16_4 slot shares bandwidth with M.2 x4. When the M.2
socket is occupied, the PCIe x16_4 will be disabled.
** The PCIe x16_3 slot supports GEN3 discrete cards and x8 devices
only.
***The PCIe x16_2, PCIe x1_1, and USB3_E56 connectors share the
same bandwidth. By default, the PCIe x16_2 slot and PCIe x1_1 slot
automatically run at x1 mode with USB3_E56 enabled for best resource
optimization.

I am running a GTX 980TI, two 400gb Intel 750 PCIE cards and a 512gb m.2 in the m.2 slot

When i bench the first pcie card i get over 2200mbps read / write, on the 2nd card i get approx 450mbps.

this sounds too slow for it to be running in x8?

[Bishop Crane]

What CPU do you have, and which slots are the devices in?
As is changes slightly how things work.

The key thing is that the PCIe x16 at the edge of the motherboard only runs at 4x maximum plus it shares bandwidth with the M.2

Also the PCIe x16_2 (the one next to the thunderbolt header) shares bandwidth with with one of the x1 slots as well as the USB3_E65 connector
The key thing from the info is that PCIe x16_2 by default runs at x1 for resource optimization

Quote

By default, the PCIe x16_2 slot and PCIe x1_1 slot
automatically run at x1 mode with USB3_E56 enabled for best resource
optimization.

Hope that helps!

[UrbanFreestyle]

Thanks for the reply, I am running an i7 5960X Processor, 

If i was to list them they would be as follows:

PCIE x16_1 - GTX 980TI

PCIE x16_2 - Intel 750 400gb

PCIE x16_3 - Intel 750 400gb

PCIE x16_4 - Empty

Onboard M.2 - 512gb Samsung SM951

 

Is there a way to disable USB3_E65 as i'm not sure i'm using that or does that controll all USB3 on the machine?

[Bishop Crane]

Fairly certain in the BIOS, under Advanced, I think its onboard devices.
There should be the option to set the bandwidth on the PCIe x16_2 slot to x4 mode, this will then disable both the USB3_E65 and the PCIe x1_1 slot

[UrbanFreestyle]

Thank you so much for your help. My end goal is to raid these two cards in a stripe so i get circa 800gb of PCIE nvme storage

[UrbanFreestyle]

21 hours ago, Bishop Crane said:

Fairly certain in the BIOS, under Advanced, I think its onboard devices.
There should be the option to set the bandwidth on the PCIe x16_2 slot to x4 mode, this will then disable both the USB3_E65 and the PCIe x1_1 slot

So i managed to get this running, seems to be capable of a little more if i could have run at x8 but it is still going at 1500mbps read and 900mbps write.

Thanks so much for your help. REALLY appreciate it!