Problems with Z790-Pro and GPU

[Zaister]

I'm looking for help with a PC I recently built. I have an ASUS TUF Gaming Z790-Pro WIFI mainboard, a Core i7-14700K and an ASUS TUF Gaming GeForce RTX 4070 Ti OC GPU.

The problem is that the mainboard does not recognize the GPU when put in the primary PCI slot. The boot process stops on the white light. If I connect the monitor to the internal video port, the machine boots, but there is no trace of the 4070 being present, neither Windows device manager nor Linux lspci can detect it. This happens not only with the 4070, but also with other cards I've tried.
The video card does work, however, when I put it into the secondary PCI slot, although with a significant performance loss.

This is already the second Z790-Pro mainboard I'm trying this with, both behave the same. I have updated the mainboard to the latest BIOS version, 1658 (dated 05/31).

I have my main NVME disk in the M2_1 slot, could that be the problem? I'm not fully sure about how the bifurcation stuff actually works.

Any ideas how I can get this setup to work properly? Any help would be appreciated.

[Silent_Scone]

Hi @Zaister 
As you've already replaced the mainboard we can likely rule-out this as the issue. Are you using a riser cable for the GPU or is it directly connected?

Which power supply? Are you using a native 16-pin 12VHPWR connector or the provided adapter?

if using the supplied adapter, ensure all PCI-8 pins are connected correctly.

Equally, if using a native 16-pin 12VHPWR, ensure it is fully inserted and the red LED is not lit on the GPU.

Remove the CPU and inspect the CPU pin-pad and CPU contact pads. Remount the CPU and cooler whilst checking for consistent mounting pressure as per the cooling vendors guidelines.

[Zaister]

Thanks, @Silent_Scone.

The GPU is connected directly, no riser. I am using a be quiet Straight Power 12 850W PSU, and yes, I'm also using the 12-pin cable that came with the PSU. The GPU also works fine if inserted into another computer while connected to the 12-pin cable from this computer (I have only one appropriate PSU), and the red light is off, too. So I think I can rule out this connection.

I will check the CPU socket, thanks for the tip.

[owu]

Were you able to solve this problem, if so, please tell me😭

[Silent_Scone]

Yes, please check the CPU socket. If no joy, I can only suggest contacting service again for your region.