[SOLVED] Why does all 4 of my GPU PCIe slots on my Z390 Godlike Motherboard recognize my RTX 3090, except for lane slot # 1?

[SeriousGaming101]

Hello all,

This is my Z390 Motherboard:
https://www.newegg.com/p/N82E16813144209

My ultimate goal is to fit 3 RTX 3090s on this Z390 Godlike motherboard for mining:

Today I tried an experiment. I have listed the PCI-E lanes numbers in the picture below for reference:

https://imgur.com/a/9N2Yzgy

View: https://imgur.com/a/9N2Yzgy


Normally I put my 1 RTX 3090 on the PCIe lane #4 on the far right side --->>>, but today I moved it over to the PCIe lane#1 on the far left side <<<---

https://imgur.com/a/9pgzyNt

View: https://imgur.com/a/9pgzyNt


The problem is, every time i boot up my PC while the GPU is in PCIe lane#1, it brings me to this MOBO BIOS screen and WONT load into windows as normal (even after several restarts):

https://imgur.com/a/bQSro8y

View: https://imgur.com/a/bQSro8y


According to the "Board Explorer", when the GPU is in PCIe lane #1, it wont even recognize that it is there (and also wont recognize the 2TB M.2 NVME to boot into):
Click the image below for more images:

https://imgur.com/a/KExRkxf

View: https://imgur.com/a/KExRkxf

If you look closely at the images above it says that PCIe#1 lane is a "PCIe x 1 slot" while at the same time PCIe lanes #2,3,4 are ALL "PCIe x 16 slot"

I removed the GPU from my PCIe#1 lane and the GPU works perfectly fine installed in PCIe lanes #2,3,4 (just not the lane #1 and I dont know why)

These are the pictures below of the GPU working fine with the other lanes and also recognizing the 2TB M.2 NVME to boot into:

https://imgur.com/a/POfXEcC

View: https://imgur.com/a/POfXEcC


So my question is,

1. Why doesnt the GPU boot into Windows when it is in PCIe#1 lane? And why it doesnt recognize my 2TB M.2 NVME when its in that lane?
2. Why does the Z390 Godlike motherboard say that PCIe#1 lane is a "PCIe x 1 slot" while at the same time PCIe lanes #2,3,4 are ALL "PCIe x 16 slot"?
3. Why does my PC boot normally into Windows and also recognize the 2TB M.2 NVME while only in PCIe lanes #2,3,4?
4. *How do I make my RTX 3090 GPU work with the Z390 Motherboard while the GPU is inserted into PCIe#1 lane?

Remember, my ultimate goal is to fit 3 RTX 3090s into the Z390Godlike Motherboard.

 

[kerberos_20]

it all depends on how its wired and how many resources are available to those lanes
did u enable above 4G in bios settings? it mostly fixes pcie lanes issues

 

[SeriousGaming101]

it all depends on how its wired and how many resources are available to those lanes
did u enable above 4G in bios settings? it mostly fixes pcie lanes issues

whats 4G?

 

[kerberos_20]

whats 4G?

its device mapping adress space, it allows to map 64bit devices above 4GB ram adress space

 

[SeriousGaming101]

its device mapping adress space, it allows to map 64bit devices above 4GB ram adress space

I still don't understand what that is. Can you show me a step-by-step way to fix this so even a dog would understand?

 

[kerberos_20]

oh ok, its in bios settings

press F7 for advanced settings
Settings -> Boot -> Boot mode select -> UEFI
Settings -> Advanced -> PCI subsystem Settings -> Above 4G Memory/Crypto currency mining -> Enabled

thats all there is to it,
if 4th slot (x16 wired as x1) wont post with GPU, then its mainboard limitation, port can be still used for mining, just no video output