Question GPU-Z BUG or BIOS PCIe 5.0 MOBO

[jaquith]

My copy of GPU-Z (version 2.51.0) reports Bus Interface as "PCIe 4.0 @ 8x." First my ASUS ROG Extreme Z790 has a PCIe 5.0 x16 Bus Interface and my RTX 4090 has a PCIe 4.0 x16 Bus Interface. Correct reporting should be PCIe 5.0 x8 which is equivalent to PCIe 4.0 x16 in bandwidth. Yesterday I watched a video posted by Der8auer on YouTube entitled "I tried to repair my RTX 4090 and killed it " where we are using the same MOBO and RTX 4090 and he too has the same reporting of "PCIe 4.0 @ 8x." Also obviously I double checked the "shared" limits for my MOBO. I'm using the DDR4 DIMM.2_SLOT with 2x 4TB/ea M.2 drives and the M.2_1(SOCKET3) with an M.2 all M.2's are PCIe 4.0 types. Notes: M.2_1 shares bandwidth with PCIEX16(G5)_2. When M.2_1 is enabled, PCIEX16(G5)_2 will be disabled. The RTX 4090 is installed in the PICEX16(G5)_1.

=> While typing this the only thought I have is to see if there's a PCIe 4 .0 (G4) / PCIe 5.0 (G4) BIOS selection. Unfortunately the manual doesn't list BIOS entries to search handily.

So my question is has anyone with a Z790 MOBO experienced the same problem?

GPU-z (image)

https://imgur.com/a/ujlhR9e

View: https://imgur.com/a/ujlhR9e


New:
GPU-Z https://www.techpowerup.com/gpuz/details/m3s3k
CPU-Z https://valid.x86.fr/hsghtk

Old:
GPU-Z https://www.techpowerup.com/gpuz/details/6x7h8
CPU-Z https://valid.x86.fr/9mm3cz

 

[kerberos_20]

pcie 4.0 is correct, your GPU doesnt support PCIE 5.0

 

[jaquith]

pcie 4.0 is correct, your GPU doesnt support PCIE 5.0

Umm I know ... I said "my RTX 4090 has a PCIe 4.0 x16 Bus Interface. " The issue is the GPU-Z reporting of PCIe 4.0 x8 on an otherwise PCIe 5.0 x16 MOBO when in fact it's the equivalent of "PCIe 4.0 x32" in actual bandwidth. So I'm trying to determine the underlying reporting problem(s). There's no way Der8auer and I with different RTX 4090's have faulty PCIe slots both reporting PCIe 4.0 x8. So my feeling this is either a GPU-Z bug incorrectly reporting PCIe 5 slots to PCIe 4 cards or a BIOS issue. AKA BUG

 

[Eximo]

That is showing 8x at PCIe 1.1 speeds. This is normal under idle conditions. "PCIe x 16 4.0 @ 8x 1.1" Telling you what it is capable of and the current speed.

Run a benchmark while looking at GPU-Z and see if it increases to 4.0 x16.

 

[jaquith]

That is showing 8x at PCIe 1.1 speeds. This is normal under idle conditions. "PCIe x 16 4.0 @ 8x 1.1" Telling you what it is capable of and the current speed.

Run a benchmark while looking at GPU-Z and see if it increases to 4.0 x16.

That won't change the number of lanes. Example the "1.1, 2.0 or 4.0" are power states. Here's my RTX 3090 just doing nothing, note the PCIe 4.0 x16 (1.1) and it's on an Z690 which is also PCIe 5.0. So the question is a GPU-Z Z790 reporting bug, an ASUS BIOS bug / setting or even an RTX 4090 BIOS bug??

RTX 3090 (PCIe 4.0 x16) on and ASUS TUF Z690 (PCIe 5.0 x16) .. showing PCIe 4.0 x16.

https://imgur.com/iSKLNjG

View: https://i.imgur.com/iSKLNjG.jpg

 

[kerberos_20]

that is because on intel you do loose 8 lanes if you use nvme, on your mobo thats m2_1 slot.

 

[Eximo]

Seems to be common with Z790 ASUS boards. They are offering PCIe 5.0 support in the first M.2 slot, the second M.2 slot is the one you should use. It is still connected to the CPU, but only at PCIe 4.0.

Seems like a waste of a slot to me. Would rather have another chipset connected drive.

Much like my Z490 board, without an 11th gen CPU, the first slot is connected to nothing.

 

[Karadjgne]

Z790 pch is 20x Gen4, 8x Gen3
Raptor-lake is 16x Gen5, 12x Gen4.
Don't see why there'd be an issue, should be able to run a gpu @ 4.0 x16 and NVMe at 4.0 x4 from the cpu. Not unless somebody did something astronomically stupid and chopped the Gen5 lanes if Gen5 isn't used, forcing a NVMe to use the 4.0 x4 and a Gen4 gpu to use the remaining 4.0 x8, leaving the 5.0 x16 untouched.

 

[kerberos_20]

Z790 pch is 20x Gen4, 8x Gen3
Raptor-lake is 16x Gen5, 12x Gen4.
Don't see why there'd be an issue, should be able to run a gpu @ 4.0 x16 and NVMe at 4.0 x4 from the cpu. Not unless somebody did something astronomically stupid and chopped the Gen5 lanes if Gen5 isn't used, forcing a NVMe to use the 4.0 x4 and a Gen4 gpu to use the remaining 4.0 x8, leaving the 5.0 x16 untouched.

well ye they chopped it...nvme on first slot shares lanes with second pcie x16 slot
and if you use second x16 or first nvme slot...it wont matter which one, first pcie slot gets half lanes...i have no idea why they didnt offer atleast two 5.0 m2 slots if its wired this way...
anyway other m2 slots (if any) are pcie 4.0 and wont ninja first pcie x16 5.0 lanes

 

[Karadjgne]

Ok, I change my opinion. It just went from astronomically stupid, to totally asinine. The chances of anyone using those motherboards strictly for the cpu, using igpu and a Gen5 NVMe are So small as to be 1 or 2 ppl on the planet. It wouldn't be that difficult to specify in bios which lanes got which pcie at the cpu level, they use the same wiring anyway. That would at least allow 4.0 x16 and 5.0 x4 or 5.0 x16 and 4.0 x4. The coding is already there in bios, has been for years, you get to assign pcie Gen to the PEG. Simply add in the assignment options for M.2_1.

 

[kerberos_20]

there are physical wires, intel is just dumb releasing cpu with only 16 5.0 lanes

 

[Brakedown]

My copy of GPU-Z (version 2.51.0) reports Bus Interface as "PCIe 4.0 @ 8x." First my ASUS ROG Extreme Z790 has a PCIe 5.0 x16 Bus Interface and my RTX 4090 has a PCIe 4.0 x16 Bus Interface. Correct reporting should be PCIe 5.0 x8 which is equivalent to PCIe 4.0 x16 in bandwidth. Yesterday I watched a video posted by Der8auer on YouTube entitled "I tried to repair my RTX 4090 and killed it " where we are using the same MOBO and RTX 4090 and he too has the same reporting of "PCIe 4.0 @ 8x." Also obviously I double checked the "shared" limits for my MOBO. I'm using the DDR4 DIMM.2_SLOT with 2x 4TB/ea M.2 drives and the M.2_1(SOCKET3) with an M.2 all M.2's are PCIe 4.0 types. Notes: M.2_1 shares bandwidth with PCIEX16(G5)_2. When M.2_1 is enabled, PCIEX16(G5)_2 will be disabled. The RTX 4090 is installed in the PICEX16(G5)_1.

=> While typing this the only thought I have is to see if there's a PCIe 4 .0 (G4) / PCIe 5.0 (G4) BIOS selection. Unfortunately the manual doesn't list BIOS entries to search handily.

So my question is has anyone with a Z790 MOBO experienced the same problem?

GPU-z (image)

https://imgur.com/a/ujlhR9e

View: https://imgur.com/a/ujlhR9e


New:
GPU-Z https://www.techpowerup.com/gpuz/details/m3s3k
CPU-Z https://valid.x86.fr/hsghtk

Old:
GPU-Z https://www.techpowerup.com/gpuz/details/6x7h8
CPU-Z https://valid.x86.fr/9mm3cz

Hi...
I have the same problem on my ROG Maximus z690 Extreme with Core i9 12900KS. I did a test without connecting any m2 and it continues with the bus at x8. I've been researching and I think it's the new BIOS update to accept the 13th generation processors that is giving this problem. Hope they fix this bug.

 

[Brakedown]

My copy of GPU-Z (version 2.51.0) reports Bus Interface as "PCIe 4.0 @ 8x." First my ASUS ROG Extreme Z790 has a PCIe 5.0 x16 Bus Interface and my RTX 4090 has a PCIe 4.0 x16 Bus Interface. Correct reporting should be PCIe 5.0 x8 which is equivalent to PCIe 4.0 x16 in bandwidth. Yesterday I watched a video posted by Der8auer on YouTube entitled "I tried to repair my RTX 4090 and killed it " where we are using the same MOBO and RTX 4090 and he too has the same reporting of "PCIe 4.0 @ 8x." Also obviously I double checked the "shared" limits for my MOBO. I'm using the DDR4 DIMM.2_SLOT with 2x 4TB/ea M.2 drives and the M.2_1(SOCKET3) with an M.2 all M.2's are PCIe 4.0 types. Notes: M.2_1 shares bandwidth with PCIEX16(G5)_2. When M.2_1 is enabled, PCIEX16(G5)_2 will be disabled. The RTX 4090 is installed in the PICEX16(G5)_1.

=> While typing this the only thought I have is to see if there's a PCIe 4 .0 (G4) / PCIe 5.0 (G4) BIOS selection. Unfortunately the manual doesn't list BIOS entries to search handily.

So my question is has anyone with a Z790 MOBO experienced the same problem?

GPU-z (image)

https://imgur.com/a/ujlhR9e

View: https://imgur.com/a/ujlhR9e


New:
GPU-Z https://www.techpowerup.com/gpuz/details/m3s3k
CPU-Z https://valid.x86.fr/hsghtk

Old:
GPU-Z https://www.techpowerup.com/gpuz/details/6x7h8
CPU-Z https://valid.x86.fr/9mm3cz

I found a very interesting article about PCIe. I recommend reading.

NVIDIA GeForce RTX 4090 PCI-Express Scaling

The new NVIDIA GeForce RTX 4090 is a graphics card powerhouse, but what happens when you run it on a PCI-Express 4.0 x8 bus? In our mini-review we've also tested various PCI-Express 3.0, 2.0 and 1.1 configs to get a feel for how FPS scales with bandwidth.

www.techpowerup.com

See ya.

 

[kerberos_20]

I found a very interesting article about PCIe. I recommend reading.

NVIDIA GeForce RTX 4090 PCI-Express Scaling

The new NVIDIA GeForce RTX 4090 is a graphics card powerhouse, but what happens when you run it on a PCI-Express 4.0 x8 bus? In our mini-review we've also tested various PCI-Express 3.0, 2.0 and 1.1 configs to get a feel for how FPS scales with bandwidth.

www.techpowerup.com

See ya.

well pcie bandwith is used when gpu has to receive data from cpu (system ram), games doesnt directly render from system ram...so thats why theres not much fps difference in x8 vs x16, it might have some latency difference with small packets, which would make lower 0.1%low/minimum fps, but resizeable bar should cope with that fine