Question GPU running at 4 x8 instead of x16 ?

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Cigarette_Smoking_Man

Cigarette_Smoking_Man

Feb 4, 2024
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I just noticed an issue with my GPU not running at the correct speed. It is running at 4 x8 instead of x16. I first became aware of the issue when I turned my PC on and I got a message to say my gpu was running at PCIE gen 3 speeds. I am not sure why the change happened but I was alerted to it on startup. I managed to manually change the generation in the bios for 4.0 and thst worked. However the speed is only x8 even under load. My troubleshooting to date is:

  • Reseat the gpu a d clean contacts and slot
  • Reseat the cpu
  • Clear Cmos
  • Update bios
  • Change motherboard
  • Remove all nvme drives except for boot drive in slot 1.

Would anyone have any idea what's going on here? I've ruled out motherboard because I got a new one, and I doubt Asus would have given me two bad boards.

Thought it must be a configuration issue, but I have tired with only one nvme in slot 1 to act as boot drive and no change.

System
CPU: 7800x3d
Motherboard: Rog Strix b650e-e
RAM: corsair Vengeance 32gb 6000nhz
GPU 7900xtx red devil
Storage: crucial P5 500gb and crucial P3 2tb

Any help here would be great. I know it's not a massive performance decrease, but I have paid for the performance so would like to get it.
 
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Page vii of the manual for your board: "When M.2_3 is occupied with an SSD device, PCIEX16_1 will run x8 only." Emphasised again in picture form on page xi.

PCIEX16_1 is the top slot, and M.2_3 is the port between the lower x16 slots.

Are you sure you're only putting a drive into M.2._1? That's the one above the top graphics card slot.
 
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Bad board or bad card. Not a software issue if it's happening at the BIOS level. Update/reflash the motherboard (reflash current if there's nothing newer, or try rolling back one version) and if that doesn't fix it find a friend or bring the card to a local shop to confirm it's not the GPU... then tell ASUS to stop sending you trash.
 
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Cigarette_Smoking_Man said:
Yeah positive, The nvme is in the m.2_1. I was very careful to where the m.2 was installed. I've no sata ports or anything else connected.

I'm really stumped to what the issue could be.
Click to expand...
I'd suggest trying the GPU in the other x16 slot, and if that doesn't work trying the M.2 boot drive in the other M.2 slots. If you've still no luck, try and get hold of a different x16 graphics card to eliminate that.
 
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Yesterday I did a full DDU uninstall of the drivers in case their was an issue there, no joy with that.

I set the PCIE slot to Gen 3 in BIOS and still runs at x8

Next I will try GPU in second slot and moving boot drive to another NVME slot. If that doesn't work I will borrow another x16 GPU and see what speeds that is running at.

Hoping it isn't an issue with GPU as that will be the longest thing to RMA. I'm wondering if it is an ASUS issue. After some googling there seems to be a lot of people reporting this issue with ASUS boards.
 
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It may not matter much. When 4090 first came out they were trying to figure out how much slower it would run in a pcie3 machine. There was some technical reason they could not just change it from pcie 4 to pcie 3 so what they did was run pcie 4x8 to simulate pcie3x16. Some guys rather than change bios setting put tape over some of the connectors on the card.
The results were there was almost no difference.

I suspect the results would be similar for your card.

So the best would be to get a RMA but you then have to suffer with a very long time to be without a card. You also have the check the card if there any kind of tiny crack in the connector that damaged some of the traces they will just blame it on user error. This is why large video cards now have support brackets.
 
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bill001g said:
It may not matter much. When 4090 first came out they were trying to figure out how much slower it would run in a pcie3 machine. There was some technical reason they could not just change it from pcie 4 to pcie 3 so what they did was run pcie 4x8 to simulate pcie3x16. Some guys rather than change bios setting put tape over some of the connectors on the card.
The results were there was almost no difference.

I suspect the results would be similar for your card.

So the best would be to get a RMA but you then have to suffer with a very long time to be without a card. You also have the check the card if there any kind of tiny crack in the connector that damaged some of the traces they will just blame it on user error. This is why large video cards now have support brackets.
Click to expand...
It's not so much if there is a difference today, the cad works very well in the x8 configuration and I am getting the expected FPS in games in comparison with other benchmarks of this card. My concern is will it have an impact in the future as technology improves, as I don't plan on upgrading it anytime soon. I would also really like to find out what is causing the issue.

I just thought there the card has dual bios and I haven't tested it with its second bios that might be something to try .
 
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Any future technology would have to somehow increase the speed of the GPU or its memory. That is all hardware. Changing a software driver is not going to change the amount of data that is being transferred very much. It won't matter until you buy a new video card and then unless it is slot on your motherboard your new card will have all 16 lanes working.

Will be interesting to see what new generations of video cards use.
There has been lots of discussion on does it even matter if your pcie slot is pcie 4 or the newer pcie5. The theory is that even if they double the 4090, which most people say it will not be double, it can still run on pcie4x16 so the actual need for pcie5 slots is likely many years away.

It is unlikely it is the bios. Those are more related to the clocking and the power use. You have nothing to lose by trying it.
Most pcie issues are physical damage, it could be some chip.

Maybe carefully inspect the card and the slot. Maybe you get lucky and there is some dirt or something simple blocking some of the pins
 
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Moonstick2 said:
Not according to the ROG STRIX B650E-E GAMING WIFI specs: "2 x PCIe 5.0 x16 slots (support x16 or x8/x4 modes)**"
with the asterisk referring to the x8/M.2_3 sharing matter.
Click to expand...
What do you think that means?
It means x16 mode in first PCIE x16 slot.
If second PCIE x16 slot is used, they switch into x8 (first PCIE x16 slot) and 4x (in second PCIE x16 slot).
Second PCIE x16 doesn't support more than x4 mode.

It's described in user manual page 1-7.
https://dlcdnets.asus.com/pub/ASUS/...M_WEB.pdf?model=ROG STRIX B650E-E GAMING WIFI
 
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SkyNetRising said:
What do you think that means?
Click to expand...
I took it to mean that either slot with a single GPU will run in x16 mode, and if both slots are populated, they run in x8/x4.

To me, "2 x PCIe 5.0 x16 slots (support x16 or x8/x4 modes)" made them sound equivalent. For the above, "1 x PCIe 5.0 x16 (support x16 mode***) 1 x PCIe 5.0 x16 (support x4 mode)" (with the *** indicating a drop to x8 if the 2nd slot is populated same as the drop to x8 if M.2_3 is occupied), would I think have been a lot clearer.

I accept you're right (the top slot also accepts 4 times as many SSDs on a Hyper series card), though it seems to me that surely any card in the second PCIe slot should drop the upper one to x8. (I also wonder what happens if there are two GPUs and M.2_3 is occupied...)

For the OP's purposes, they're probably best off trying to get hold of some other 4.0x16 graphics card temporarily to test.
 
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