System doesn't see second 4090

[diht404]

I have server with 2 4090, motherboard: https://www.asus.com/motherboards-components/motherboards/proart/proart-z790-creator-wifi/techspec/, cpu: Intel i9 13900K. But my server doesn't see one of 4090.

Whether I use Linux or Windows, nothing changes. lspci shows only one card. In bios i found that one of 4090 use 16x PCI

(see on screen), but as i know, it should switch to 8x and 8x automatically.

[Nate152]

Hello diht404,

It looks like your second 4090 is not being detected in the bios. To confirm, you have the second 4090 installed in the second pcie x16 slot?

Double check the pcie power cables are fully connected.

You could try setting all link speeds to Gen 4.

if it's still not detected, have you tested the second 4090 to be sure it's working?

[diht404]

Hello.

Yes, the second 4090 installed in the second pcie x16 slot. We haven't tested gpus separately yet, but we have 2 identical servers and both of them see only one 4090, so it looks like problem with software or something like this.

[Nate152]

Thank you,

I see your motherboard has a pcie bifurcation setting that can be enabled and adjusted.

 The exact steps may vary depending on the motherboard model, but here are the general steps:

1. Enter the BIOS.  
2. Navigate to the Advanced tab,  System Agent Configuration menu.
3. Look for options related to PCIe bifurcation, such as "PCIe bifurcation support" or "PCIe bifurcation mode".
4. Enable the appropriate option(s) for your use case.
5. Save and exit the BIOS settings.

[diht404]

Thank you for your answer. After turning on the bifurcation, we get the following: I think it's better, but we can't see a second 4090.

[Nate152]

Thank you, it's some progress as you've got the "Not Present" to disappear.

May I ask what power supply you're using and how you have the pcie power cables connected to both RTX 4090's.

[diht404]

PSU: 2x straight power 12 1500w

The cables are connected directly from the power supply to both video cards without adapters.

[Nate152]

Thank you for the pictures, that is a very good power supply, platinum rated with two pcie 5.0 connectors and comes with two 12VHPWR pcie 5.0 cables.

Do you have an ssd installed in the M.2_1 slot? If so, set the link speed to Gen 4 as well.

If the second gpu is still showing x0, it would be good to test both gpu's in the first pcie x16 slot and test with both pcie 5.0 power cables.

[hatchhozzen]

Experiencing a Blue Screen of Death (BSOD) error on your computer could be due to various reasons, and having two sticks of RAM installed might not necessarily be the cause. BSOD errors are typically associated with hardware or software issues, and RAM is just one component that can contribute to these problems.

Here are some steps you can take  to troubleshoot and address the issue:

1. Check for Loose or Improperly Seated RAM:

   • Ensure that both sticks of RAM are properly   decatur pdr repair    seated in their respective slots on the motherboard. Sometimes, loose or incorrectly installed RAM modules can cause instability.

2. Run a Memory Test:

   • Use a memory diagnostic tool like Windows Memory Diagnostic or MemTest86 to check for any issues with your RAM. These tools can help identify if there are any faulty memory modules.

3. Update or Roll Back Drivers:

   • Outdated or incompatible drivers can cause BSOD errors. Make sure all your hardware drivers, especially those related to your motherboard and RAM, are up to date. If you recently updated a driver and started experiencing BSODs, consider rolling back to the previous version.