X670E Taichi - GPU stuck in PCIe 8x

Hello all I didn't see anything about this problem for board on this forum or any other place on the internet during my search so I'm posting here. I have the 1.11 version of the X670E Taichi bios with an Nvidia 4090. All 4 of the NVMe slots are currently occupied, but the second PCIe 5 x16 slot is unoccupied.

It's to my understanding only the two slots share 16 lanes and both will switch to 8x/8x if the second is occupied at any time. I looked in the bios but only see a switch for the PCI version speed, and for the following lane configurations: Auto, 8x/8x, 8x/8x/4x, 4x/4x/4x/4x. None of these options make sense besides the 8x/8x since the switch only connects to two slots, but CPU-z is showing my card is running at a current PCIe 4.0 link width of 8x. The link speed is 2.5GT/s at idle, but will rise to 16GT/s when the GPU is working.

I didn't bother to check to see if the PCIe switch options were different before upgrading to the 1.11 BIOS, but I didn't think this would be a problem. I just had a friend send me a picture of his CPU-z info and he has the same bios version as me but his card is running at PCIe 4.0 x16. He only have 1 or two NVMe drives at most while using a different CPU and less ram.

Misc info:
CPU: 7950X
RAM: 64GB G.Skill cl30 @ 6000 EXPO

for some reason asrock doesn't have an x16 option in the bios. auto should be x16 if no lanes are shared.


use gpu-z and use the load test to verify link status that it truly maxes at pcie 4 x8 on full load.

here is something you can try. go into nvidia control panel. go to manage 3d settings and scroll down to the power management mode. change it from normal to prefer maximum performance.

RESTART the system and then check for link speed.if it works like it did for me it should get the full x16 link speed.

i had this issue with a 7600x and a 4090. granted i had a few other weird issues as well, but at the end of the day the cpu was faulty and mishandling pcie lanes. replacing the cpu fixed all my issues.

Running the beta bios didn't help. Makes me think I need to reseat my cpu...

I'm going to just leave it alone since I tested the bandwidth needed in blender and it's only using 1% of the bus while rendering. Peaked at around 20% so it's unnecessary to get 8x on that card.

I might try disconnecting my ssd sata drives to see how it behaves.

reseating didn't work. I tried just the 4090 in slot 2 and it's showing 8x as well.

hmmm

I just tried reseating the cpu. All the pins and pads look perfect. Still a no go. I put in an rma for the cpu. I'm thinking it's the cpu from everything I've gathered.

Newegg was nice enough to allow me to order another cpu that they'll refund once they receive mine. So no down time in that regard.

I'll report back.