GPU stuck in X8 no NVME drive, no PCIE devices plugged in

[tonycstech]

Z690 Maximus
i9 12900KS CPU
GPU stuck in X8 instead of X16. You can see it in the BIOS screen.
No NVME drivers.
No PCIE devices plugged in.
Used latest GPUZ to confirm the issue.

Tested PCIE lanes to the CPU with a tester, PASS
Tested GPU for PCIE lanes with a tester, PASS
Tried another GPU,  same result.
Update to latest firmware, same result.

Anymore ideas ?
Bios tweak maybe ?

[theroc44]

on the z690 hero motherboard according to the manual, if anything is in the PCIEX16(G5)_2, the PCIEX16(G5)_1 automatically falls to X8. According to the pic you provided you have something in the PCI-E 5.0X8 port 4- the Pericom port is the reason you are at X8. What ever device that is. It says -IN USE, that will automatically push the PCIE5.0 x16 slot to x8.

[tonycstech]

I dont know which port is PCI-E 5.0X8 port 4 but your assumption is based on not reading what i wrote.
As i said over and over again, with NOTHING plugged into the board, GPU is at X8
I repeat, NOTHING. only GPU plugged in to 1st slot which should run at X16

[FixItWorse]

Ok, is this the UEFI telling you that the card is running at 8x?

Because if nothing else is plugged into the board then that's as far as you can get. I think that's what has some people confused.

Also, I believe, in the Onboard Devices section of UEFI there should be a setting for PCIE Bifurcation. Be sure that is set to auto and not 8x/8x.

If it's still the case that regardless of no other slots being populated, (that bifurcation of the lanes is stuck on) and clearing CMOS and pulling the CMOS battery doesn't help, restore the UEFI via the "BIOS Flashback" method, it's a lot more thorough of a flash than a typical UEFI update.

[theroc44]

I believe you that nothing else is plugged in. But according to the picture provided the bios is showing something occupying the second  PCIE 5.0 x8 slot. There are two ways to check. One in the bios under system agent, what is the second pcie 5.0 slot status is it, in use and at what speed x8,x4 etc. Or in the AIDA app if you could expand the image you posted earlier of the PCIE 5.0 slot that stated pericom. That may reveal exactly what device is registered under that x8 slot. For example as in my aida 64 pic, the expanded information shows 4090 msi suprim at x8 and m.2 5.0 at x4  (PORT 4 is the second pcie expansion slot x16)  I see that you have a Samsung m.2 installed. Which slot is it plugged into M2_1,M2_2 or M2_3 ?

[tonycstech]

OMG man, that picture is taken when something is indeed plugged in.
For goodness sake, when i remove everything except GPU, result is the same.
That picture, throw it out of your head please. Plugged in or not it makes no difference, i tried already.
No option for bifurcation either.

[FixItWorse]

Yes, theRoc is asking for clarification on what the Pericom device is.

Small mistake I made when I gave you my solution, was to check the Onboard Devices area, well the Hero doesn't have that option, instead you get PCIE-Gen5 Redriver, which you should set to Disabled.

If it's Enabled, that COULD be the strange device showing up in Aida64 occupying the second slot, but I have a Z690 Strix-E, not a Hero, so I've got no idea how the hardware enumerates when that is enabled, so I'm not certain at all but it's worth a look for sure.

[tonycstech]

already disabled by default.
here is a screenshot proving nothing other than GPU is plugged in

[FixItWorse]

Ok, I see.

Just out of curiosity, how are you booting Windows to get to Aida?

[tonycstech]

SSD
I can boot into USB linux, it will say same thing with no SSD's pluged in.

[FixItWorse]

Ok, so if your Nvme drive is in M2.2 and not M2.1, and you're still stuck at 8x, the only thing you can really do is try first update to the most recent UEFI if you haven't already, and try the BIOS Flashback method to restore the UEFI and see if it changes.

If nothing does, your only remaining option is to contact ASUS support and set up an RMA.

I did a bit of reading for you, and it appears that others out there have had a similar issue with 4080/90's and being pinned to 8x. And a few confirmed the fix to be a board swap.

If it's any consolation, I recently did a board swap on my Strix-E, for the same board, and this time around I decided to try the system with M2.1 populated and running my 3080 Ti on 8x, (just because I like to tinker, no other reason) and I have literally zero real world performance deg. in the games that I play anyways.

That's at 4K 120Hz, Halo Infinite (Native 4K), and Alan Wake 2 (using DLSS) at the moment.

Don't know if the same goes for high end 40 series, but that's been my experience.