Crosshair Hero VIII PCIE problem

[fredepf]

Hello .

I have a Crosshair Hero VIII . Bios 1302,Ryzen 9 3950X (No Bend pin), RX5700XT, 32gig corsair vengeance.
I am unable to run my video card in the upper slot at PCIE 4.0 16X
The card run at PCIE 4.0 8x .
All other slot are empty, i have 1 nvme m.2 ssd 1 tb in the upper slot.
but thats it...

I set evething in the bios but it show the PCIE1_16x at Native 8X .
I RMA the Board and got a new one and the problem are still there.

Any idea?
Thanks for your Help

[fredepf]

RedSector73 wrote:
Thank you for the information. From it, I see, a thing left that maybe a long shot or nothing as well, anyway your ram
CMW32GX4M4K3733C17 is not on the QVL for memory for both Asus website for CH8 or AMD for Ryzen 3 series
https://www.amd.com/en/products/ryzen-compatible-memory/ready-for-3rd-gen-amd-ryzen

There are four modules, perhaps lets try 2 (in second and fourth slot from CPU) and see if this changes anything and if this does not work, let's try not running DOCP just default and see if this changes anything.

If the above test fails to fix, then I would try borrowing another graphics card to see the issue is there, and
from the information given, I'm all out of ideas if this does not resolve the issue or pinpoint the source for you.

I do all the test and everthing is ok and it don't fix the problem.
Thanks for your help

[squawker]

Hi fredepf,

If your SSD NVMe Sabrent is on the M2_1 socket (Manual pag 1-2), it is sharing the 16 CPU PCIe’s lanes with your 5700XT, and the graphic card will operate at 8X, instead of 16X.

Try to move it to M2_2 socket, the lower M2_2 socket and see if this correct the issue.

Good luck.

[RedSector73]

squawker wrote:
Hi fredepf,

If your SSD NVMe Sabrent is on the M2_1 socket (Manual pag 1-2), it is sharing the 16 CPU PCIe’s lanes with your 5700XT, and the graphic card will operate at 8X, instead of 16X.

Try to move it to M2_2 socket, the lower M2_2 socket and see if this correct the issue.

Good luck.

Might have wrong motherboard manual. CH8 - Chapter 1 Page 1-8



The lower M2 is controlled by x570 chipset and is slower. Also, as you can see there is no issue with x16 and using M2 in the top.

[squawker]

The AMD AM4 processors have 16 PCIe lanes at maximum and if the M2_1 socket has access to these lanes, the graphic card will operate at X8.
So, my suggestion to change to M2_2 socket and with the graphic card in the PCIEX16_1 slot.

Also the 570 chipset is PCIe 4.0 with plenty of lanes and i doubt if it will be slower with most of NVMe SSD’s (even the PCIe 4.0).

[fredepf]

squawker wrote:
The AMD AM4 processors have 16 PCIe lanes at maximum and if the M2_1 socket has access to these lanes, the graphic card will operate at X8.
So, my suggestion to change to M2_2 socket and with the graphic card in the PCIEX16_1 slot.

Also the 570 chipset is PCIe 4.0 with plenty of lanes and i doubt if it will be slower with most of NVMe SSD’s (even the PCIe 4.0).

The Ryzen 3950X have 24 PCIE Lanes . and X570 16 Lanes . even if i have 2 NVME SSD it's suppose to work at 16X

I alerady try to change NVME to M2.2 and the Graphic card run at 8X this don't fix my problem
I know this don't have effect on Perf but i want to find why my GFX only run at 8X .

Thanks for your help

[squawker]

Yes the 3950X CPU has a total of 24 PCIe 4.0 lanes, of which 4 are used for the interconnect to the X570 chipset, leaving 20 lanes Gen 4.0 for other utilization (USB, LAN, etc).

Only 16 lanes (PCIe 4.0) are intended for graphics cards that are connected as x16, so my remark.

My setup is a Crosshair VIII Hero Wi-Fi also with a 3950X CPU, and i have a raid (2 x Optane 900P) with an Hyper M.2 X16 adapter on the PCIEX16_2 and my graphic card run at X8, like yours.

So, my suggestion of changing the SSD for the M2_2 socket.

But if you tried this without result, after all yours attempts, its a trick issue.
Good luck.

[fredepf]

squawker wrote:
Yes the 3950X CPU has a total of 24 PCIe 4.0 lanes, of which 4 are used for the interconnect to the X570 chipset, leaving 20 lanes Gen 4.0 for other utilization (USB, LAN, etc).

Only 16 lanes (PCIe 4.0) are intended for graphics cards that are connected as x16, so my remark.

My setup is a Crosshair VIII Hero Wi-Fi also with a 3950X CPU, and i have a raid (2 x Optane 900P) with an Hyper M.2 X16 adapter on the PCIEX16_2 and my graphic card run at X8, like yours.

So, my suggestion of changing the SSD for the M2_2 socket.

But if you tried this without result, after all yours attempts, its a trick issue.
Good luck.

Ok i Understand now.
I will try another time to put NVME in M2.2 just for make sur .
DO you know what usb Device can take PCIE Lanes ?
I didnt know USB take PCIE Lanes.

Thanks for your HElp i really appreciate

[RedSector73]

squawker wrote:
Yes the 3950X CPU has a total of 24 PCIe 4.0 lanes, of which 4 are used for the interconnect to the X570 chipset, leaving 20 lanes Gen 4.0 for other utilization (USB, LAN, etc).

Not technically correct again. USB, LAN, ETC do not effect or use the graphics lanes unless as a added riser device in the PCIe bus. USB don't use or share PCIe lanes with the graphics whatsoever. 4 of PCIe go to X570 chipset which runs LAN, USB and your etc.

If you have only graphics card in PCIe than you should get x16. Having something else plugged in PCIe than it drops as per the previous attachment which uses graphics card as the example. M2 being the either slot, does not effect getting x16.

[fredepf]

RMA the board .
I hope they will fix the issue .
Thanks for your Help.