ASUS Crosshair Hero X670E M2_1 SSD Slot Only Giving x2 Connection Speed

[Banditt1976]

I have an AMD 7950x CPU, MSI 4090 Suprim, 32GB GSKILL 6000MT/s RAM & Crucial T700 2TB PCIe 5 SSD intalled in the M2_1 slot on the MB, but I am only getting a PCIe 5.0 x2 connection speed instead of the full PCIe 5.0 x4 connection speed that both the MB and SSD support. If I install the Crucial SSD into the M2_2 slot I get the full PCIe 5.0 x4 that the MB and SSD fully support. I have the MSI 4090 Suprim GPU installed in the top x16 slot where it should be. Is this some kind of limitation on the M2_1 slot if the GPU is installed in the top PCIe x16 slot? I have confirmed the connection speed and transfer speeds with both CrystalDiskInfo and CrystalDiskMark. I put a different SSD, a Samsung 980 Pro, into the M2_1 slot and that also gets a PCIe 4.0 x2 connection instead of the PCIe 4.0 x4 connection that it should be getting. I am on BIOS version 1602 and have updated the Crucial drive with its latest firmware version. Do I have a faulty M2_1 slot on my MB or is this slot limited to x2 instead of x4 for some reason?

[Jiaszzz_ROG]

Hello, @Banditt1976 

May I ask if the situation you described happened after any changes were made? For example, updating the BIOS or connecting an external device
Could you please specify how you verified the M.2_1 speed and images of the BIOS main page and the anomalies of the M.2_1 speed?
According to the ROG CROSSHAIR X670E HERO user manual, only PCIEX16_1 and PCIEX16_2 shared bandwidth.

Please also confirm if your current BIOS version is the latest one, version 1807, released on December 15, 2023.
If not, we recommend updating the BIOS and clearing CMOS to reassess the situation.
Additionally, we suggest checking if there are firmware updates for your SSDs and ensuring that you've correctly installed a heatsink on the M.2_1 slot to prevent overheating.

Thank you.