Question x16 4.0 Issues

[DARBADARBZ]

I have a 5800X3D, 6800XT, P3 Plus, and AX210 in a B550 Phantom Gaming 4 motherboard. My PCIe speed on the graphics card is x8 4.0 according to gpu-z. I've gone through some bios updates, settings and even reset my entire computer and it won't go to x16.

I have another PC with the same motherboard but with a 5600, AX200 and 6750XT and it runs at x16.
Am I missing something? Is someone able to help me?

 

[Lutfij]

B550 Phantom Gaming 4
+
I've gone through some bios updates,
For the sake of relevance, please state the BIOS version you're on at this moment of time.

P3 Plus
Your motherboard has slots M2_1 and M2_3 for your storage. Which one are you populating?

AX210
Is this a wireless adapter populating M2_2 or a card populating a PCIe slot on your motherboard?

even reset my entire computer and it won't go to x16.
Please elaborate on what you're referring to as a reset.

Am I missing something? Is someone able to help me?
What is the make, model and age of your PSU for the first build?

Have you tried clearing the CMOS for your motherboard?

 

[DARBADARBZ]

B550 Phantom Gaming 4
+
I've gone through some bios updates,
For the sake of relevance, please state the BIOS version you're on at this moment of time.

P3 Plus
Your motherboard has slots M2_1 and M2_3 for your storage. Which one are you populating?

AX210
Is this a wireless adapter populating M2_2 or a card populating a PCIe slot on your motherboard?

even reset my entire computer and it won't go to x16.
Please elaborate on what you're referring to as a reset.

Am I missing something? Is someone able to help me?
What is the make, model and age of your PSU for the first build?

Have you tried clearing the CMOS for your motherboard?

L3.61

The top one, the 4.0 one. Running in the same one as my other PC.

It's in the m.2 E Key slot.

New windows install and BIOS reset.

The 6800 XT has a HX1200i, bought used from someone 2 years ago who barely used it. The one that's working right has some random 750 watt.

CMOS has been cleared.

 

[Lutfij]

Try reinstalling your chipset drivers and then reseating the GPU.

New windows install
Windows 10 or 11? Did you recreate your bootable USB installer to rule out a corruption? Installing the OS in offline mode?

Considering you have the same boards for two builds, I'd ask you to swap over the GPU and your PSU over to the other platform and see if you get the same experience or if it goes up to x16 speeds. If nothing changes, might want to inspect the fingers for the GPU and if you see any scratches.

 

[DavidM012]

I have a 5800X3D, 6800XT, P3 Plus, and AX210 in a B550 Phantom Gaming 4 motherboard.


It could just be lane sharing. If your AX200 is a wifi card how are you hosting the os on this system:

'I have another PC with the same motherboard but with a 5600, AX200 and 6750XT and it runs at x16. '

Spot the difference? No nvme mentioned to host the OS. How does it therefore exist? Do you have a sata ssd in it?

The wireless adaptor only uses 1 pci-e lane and wouldn't bifurcate the PCI-e 16x 4.0 slot between the nvme and gpu .

In any case pci-e 4.0 8x has 0% performance difference with pci-e 4.0 16x with this gpu.

 

[cruisetung]

https://download.asrock.com/Manual/B550 Phantom Gaming 4.pdf

Page 3 Expansion Slot:

• Ryzen CPUs (Vermeer and Matisse)• 2 x PCI Express x16 Slots (PCIE1: Gen4x16 mode; PCIE3:Gen3 x4 mode)
• Ryzen APUs (Cezanne and Renoir)• 2 x PCI Express x16 Slots (PCIE1: Gen3x16 mode; PCIE3:Gen3 x4 mode)
• Ryzen APUs (Picasso)• 2 x PCI Express x16 Slots

5800X3D codename is Vermeer, 6800XT should be in PCIE1 slot. Page 8

 

[DavidM012]

If it was in the wrong slot PCI-e3 gen3 x4 gpu-z would be reporting the gpu running in pci-e 3.0 4x mode.

There is no 'problem' here.

 

[cruisetung]

PCIE 4.0 bandwidth = 2X PCIE 3.0 bandwidth

So I wonder whether if 6800XT running in PCIE 4.0 slot with 8 lanes = 6800XT running in PCIE 3.0 with 16 lanes and that's how 6800XT or motherboard chooses its running mode.

 

[DavidM012]

The second pci-e slot only has 4 lanes so it cannot hit 8x or 16x in that slot. This board simply doesn't have as many lanes as higher end boards that's likely why the 1st pci-e 1 4.0 16x slot is bifurcated with the 1st m2 2 slot it's using 4 of the other 8 lanes and since there's no 12x the other 4 lanes are probably idle.

If you switched the os to a sata ssd and removed the P3 Plus nvme it should show the gpu running 16x in gpu-z - no if nvme it will give all all the lanes back to the gpu.

but wouldn't make a lick of difference performance wise. So you aren't losing anything by running the gpu with the nvme where the 16 lanes are bifurcated 8 to the gpu 4 to the nvme.

That it's not greatly obvious in the specifications who would say it don't look right if I look at it before you actually buy it? There's no technical problem just poor communication since you'd have to do a bit of decrypting and searching to figure out what's going on.

So after you've bought 'not one of the higher end boards' well they can just say but it don't ma'er

 

[SkyNetRising]

If you switched the os to a sata ssd and removed the P3 Plus nvme it should show the gpu running 16x in gpu-z - no if nvme it will give all all the lanes back to the gpu.

On B550 Phantom Gaming 4
use of NVME drive doesn't switch PCIE x16 slot into x8 operation mode.

Use of M2_3 slot will disable SATA ports SATA3_5 and SATA3_6 though.

 

[DavidM012]

according to the documentation which might not be telling the whole story transparently. between the lines there is chatter about lane sharing on boards - and the facts are gpu-z is evincing 8x on one board - 16x on the system where the detail of what drive the os could possibly inhabit is omitted - you can infer things. And there simply aren't as many pci-e lanes as bigger boards.

well they could spill the beans if they don't want to leave us with a cliffhanger. Is there a sata ssd in the 16x system?

 

[DARBADARBZ]

according to the documentation which might not be telling the whole story transparently. between the lines there is chatter about lane sharing on boards - and the facts are gpu-z is evincing 8x on one board - 16x on the system where the detail of what drive the os could possibly inhabit is omitted - you can infer things. And there simply aren't as many pci-e lanes as bigger boards.

well they could spill the beans if they don't want to leave us with a cliffhanger. Is there a sata ssd in the 16x system?

Installed in the system is only the 4TB P3 Plus and 6800XT, as well as AX210 E KEY wifi card.

Try reinstalling your chipset drivers and then reseating the GPU.

New windows install
Windows 10 or 11? Did you recreate your bootable USB installer to rule out a corruption? Installing the OS in offline mode?

Considering you have the same boards for two builds, I'd ask you to swap over the GPU and your PSU over to the other platform and see if you get the same experience or if it goes up to x16 speeds. If nothing changes, might want to inspect the fingers for the GPU and if you see any scratches.

Win11, bootable USB.

Switching them over is my next step.