Crosshair X870E Hero PCIE lane issues

[MorkVomOrk]

Hi, 

in my brandnew PC build, there is an issue: its an #Asus ROG Crosshair X870E Hero with a Ryzen 7 9800X3D, accompanied with 64 Gigs of Corsair DDR5-6000, a Crucial T705 SSD (in M.2_1) and an Asus TUF RTX3090 OC in PCIEX16_1. All other M.2 and PCIE slots are empty.

Still CPU-Z shows, that the GFX board ist running in PCIe 4.0 x8 rather than x16. Lane sharing/bifurcation is supposed to happen only when M.2_2 and/or M2_3 are populated, but they're empty. So what's eating into the lanes of the 3090?

What's wrong here? All relevant UEFI settings are 'Auto', I've double-check the seating of the 3090 as well. 

I'd like to avoid moving the SSD somewhere else, as M.2_2.1 is the only M.2 slot fpr PCIe 5.0. Or is it caused by the active Radeon iGPU?

Any hint is welcome.

Thanks & Br, Frank

[Baalberith_NL]

When you do a stresstest on the GPU, will it go to x16? Could also be a setting in NVCP, maybe put it on performance in energie settings. Hope this might help.

Remco

[MorkVomOrk]

Hi, thanks for the ideas. Didn't change anything though. Putting load onto the GPU just alters the protocol for link speed like 1.1 => 2.0 => 3.0 rather than enabling more lanes.

Will try to re-seat the CPU as well as the GPU and move the SSD somewhere else, likely M.2_4 or M.2_5 to see whether this changes anything. But thats something for the weekend.

Br, Frank

[MorkVomOrk]

OK, most recent update:

UEFI-BIOS flashed to 1303, SSD moved to M.2_5 - still the same only PCIE 4.0 x8 to the GPU. This leaves only three options:

1. CPU badly seated or defective.

2. GPU still badly seated or defective.

3. Motherboard defective.

Will try re-seating the CPU into its AM5 socket in the next days.

Br,

Frank

[MorkVomOrk]

CPU and GPU thoroughly re-seated now as well, no change. So either CPU, GPU, or Motherboard is defective.

[ketomagik]

Im having the same issue, my GPU is stuck in PCIE 1.1 and it cause graphical glitches and HDMI sound is cracking. If I start a Heaven Benchmark, I’m getting 14fps (RTX5080) for 3 seconds until the whole pc crashes. There’s something wrong with this board. 

[Zheega]

I often have the same issue on my B650E-E (first with a Radeon 6800XT and now with a RTX 4080S), GPU is sometimes stuck at V1.1 and I get stuttering even when just in desktop mode. But sometimes everything runs great after a restart. There is something wrong with these motherboards.

[ketomagik]

Okay it seems that I fixed it somehow.

the problem occurs right after I finish installing the Nvidia Driver. I had to reset CMOS for the motherboard to allow the PCIE16X_1 to run in 5.0

I don’t understand how a graphic driver can mess with a mobo bios but hey, that’s what’s fixed it for me. 

EDIT: Nevermind, it started again after I rebooted. This X870E Crosshair Hero is just trash, I’m returning it tomorrow.

[MorkVomOrk]

There is a misunderstanding here: its the number of allocated PCIE lanes between CPU and GPU (here in PCIEx16 #1), not the protocol version. Currently there are only x8 lanes allocated in my setup rather than the x16 that the GPU requires to run at full speed regardless of load. All requirements to avoid lane switching are met (empty PCIEx16_2 and M2.2 and M2.3). 

What you are describing is the CPU, mobo and the GPU jointly switching back and forth between protocol versions (from 5.0 or 4.0 to 1.1 and back again) thus dynamically reducing or bumping bus frequencies for power saving purposes as long as there is no load on the interface. It will switch back to highest gear asap when its required and involves the GPU and chipsets drivers. Its easy to observe using GPU-Z and happens in my setup as well. This is a completely different story and no need to RMA.

[Zheega]

No. There is something wrong with PCIe initialization.

I built a new PC with the exception of the Radeon 6800XT. AMD doesn't roll back PCIe version for power saving in idle (desktop) and sometimes (randomly) the PCIe version would be lower, resulting in lower performance. If the PCIe version was 16x V1.1, I would get stuttering and terrible performance in all games and benchmarks.

Switching to 4080 Super solved nothing. If on cold boot the PCIe version is 16x 2.0 or 3.0 or 4.0, it will throttle down to 16x V1.1 in idle, but no matter what games or benchmarks I run, it will only switch up to whatever version I got stuck with on boot. If I get 16x V1.1 on boot, then it will just be 16x V1.1 until I restart and hopefully get lucky with more than 16x V1.1 after the restart. I can run any game or benchmark for however long and it won't go above 16x V1.1 no matter what. When I am lucky to get 16x V4.0 on boot, it will behave as nothing is wrong. It goes down to 16x V1.0 on idle, go to 16x V4.0 when needed.

Here is a post from someone with a MSI motherboard in 2023 with the same issue  - https://forum-en.msi.com/index.php?threads/nvidia-4090-gpu-stuck-at-pcie1-1x16.387014/