Question Discrepancy confirming GPU's PCIE bus speed between GPU-Z and Nvidia Control Panel - Which do I believe?

Jul 6, 2021
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Unfortunately, I am not able to use the first slot on my motherboard for my new card as my CPU cooler is too chonky and ends up touching the card. This got me a bit paranoid at the possibility that my card is being hampered by a lower bus speed.
My motherboard's manual: https://hostr.co/C6uAP84qrM91, seems to show that the second slot is also x16, but I know that there are some SLI nuances that affect bus speed that I do not fully understand.

Knowing that my understanding is limited, I tried a couple of approaches to confirm that my new card is running on the fastest bus. The problem here is that GPU-Z and Nvidia Control Panel do not agree on what my bus speed is.

GPU-Z claims that my pcie bus is x16: https://hostr.co/OGuPAQrpBhYs

Nvidia Control Panels says the bus is just x8: https://hostr.co/1YuYsxW2lJv6

Which of these two means should I believe? I checked in my motherboard BIOS as well and it says that the card is running at x16 PLX, so I am leaning to GPU-Z being the correct metric.

One last thing. I have a sound card inserted into slot 5 on my mobo ("PCIe 2.0 1.1 x4_1 slot"), would this interact with the bus speed of my GPU in slot 2 by any chance?

I appreciate any help you can offer. I just want to know that I am not hampering the performance of my new card because I do not understand the finer points of the PCie Bus interface and how other lanes interact.
 
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Rogue Leader

It's a trap!
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Looking at Page 1-26 of the Manual makes me think you should use the 3rd PCIe slot (2B) because its marked as Native see what that produces. However if not then with nothing else connected then 2A should be producing x16 and I would trust GPUZ.
 
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Jul 6, 2021
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Looking at Page 1-26 of the Manual makes me think you should use the 3rd PCIe slot (2B) because its marked as Native see what that produces. However if not then with nothing else connected then 2A should be producing x16 and I would trust GPUZ.
I'll give that a go and see what results in GPU-Z, thanks for digging into the manual for me. What is the significance of a slot being "native" if you don't mind me asking?
 

Rogue Leader

It's a trap!
Moderator
I'll give that a go and see what results in GPU-Z, thanks for digging into the manual for me. What is the significance of a slot being "native" if you don't mind me asking?
On Motherboards some PCIe Slots are connected directly to the PCIe lanes on the CPU, others are connected to the PCIe lanes in the motherboard chipset. The first slot is almost always connected to the CPU, and many times the 3rd slot is also connected to the CPU, hence if you install 2 cards they are both x8 since they share those 16 PCIe lanes. Because they are marked as Native while they give no explanation in the manual I'm pretty sure those 2 slots are connected to the CPU, and so if yo have nothing in the first slot the 3rd slot should provide all 16 PCIe lanes. The other slots seem to be working off of the Motherboard's chipset. The chipset slots as long as its running at 3.0 x16 should not cause any majorly perceptible handicap.

However because you're using a 30xx GPU you really want to make sure you're running in a 3.0 x16 slot as youd be somewhat handicapping it. With older GPUs this was WAY less of an issue.
 
Jul 6, 2021
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On Motherboards some PCIe Slots are connected directly to the PCIe lanes on the CPU, others are connected to the PCIe lanes in the motherboard chipset. The first slot is almost always connected to the CPU, and many times the 3rd slot is also connected to the CPU, hence if you install 2 cards they are both x8 since they share those 16 PCIe lanes. Because they are marked as Native while they give no explanation in the manual I'm pretty sure those 2 slots are connected to the CPU, and so if yo have nothing in the first slot the 3rd slot should provide all 16 PCIe lanes. The other slots seem to be working off of the Motherboard's chipset. The chipset slots as long as its running at 3.0 x16 should not cause any majorly perceptible handicap.

However because you're using a 30xx GPU you really want to make sure you're running in a 3.0 x16 slot as youd be somewhat handicapping it. With older GPUs this was WAY less of an issue.
Thank you so much for the help. I appreciate that you explained the significance of the term "native" while also making it pertinent to my current situation. One last thing if you don't mind. I'm just about to test the other native slot (slot 3), however, my soundcard is going to be in the way as it is in slot 5. Even now with the video card in slot 2 they are very close to each other and I think it is contributing to my somewhat high GPU idle temps. When I switch my GPU to slot 3, could I put my soundcard above it in slot 2 without it altering the bus bandwidth of slot 3? I know that putting it in the 1st slot might force the 3rd slot to restrict, but I'm not sure about slot 2.
 
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Rogue Leader

It's a trap!
Moderator
Thank you so much for the help. I appreciate that you explained the significance of the term "native" while also making it pertinent to my current situation. One last thing if you don't mind. I'm just about to test the other native slot (slot 3), however, my soundcard is going to be in the way as it is in slot 5. Even now with the video card in slot 2 they are very close to each other and I think it is contributing to my somewhat high GPU idle temps. When I switch my GPU to slot 3, could I put my soundcard above it in slot 2 without it altering the bus bandwidth of slot 3? I know that putting it in the 1st slot might force the 3rd slot to restrict, but I'm not sure about slot 2.
If my theory is correct you should be able to use Slot 2 and not affect the bandwidth of the GPU.

What you should do is try it first with no sound card and confirm its function. If it works correctly at x16 install the soundcard and see if that affects it.

Let me know what happens.
 
Jul 6, 2021
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If my theory is correct you should be able to use Slot 2 and not affect the bandwidth of the GPU.

What you should do is try it first with no sound card and confirm its function. If it works correctly at x16 install the soundcard and see if that affects it.

Let me know what happens.
Hey Rogue, did as you said and switched the GPU to the third slot (the black one that is labeled native), I also removed the soundcard. GPU-Z now reads that the card is running at x8. I am going to swap it back to the second slot and install the soundcard in the last slot to see if that affects my bus speed.
 
Jul 6, 2021
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If my theory is correct you should be able to use Slot 2 and not affect the bandwidth of the GPU.

What you should do is try it first with no sound card and confirm its function. If it works correctly at x16 install the soundcard and see if that affects it.

Let me know what happens.
Tested again with GPU-Z now that the card is back in the second slot, running at x16 once again, even with the soundcard installed in the bottom full-length PCIE slot. I guess the final question I have for you is am I going to see any sort of tangible performance hit for having the card in this non-native PCIE slot even though it is running at x16 3.0?
 
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Rogue Leader

It's a trap!
Moderator
Tested again with GPU-Z now that the card is back in the second slot, running at x16 once again, even with the soundcard installed in the bottom full-length PCIE slot. I guess the final question I have for you is am I going to see any sort of tangible performance hit for having the card in this non-native PCIE slot even though it is running at x16 3.0?
Nothing you would ever notice. It would show up in a benchmark, but we are talking rounding error level difference. You're good.
 

JWNoctis

Upstanding
Jun 9, 2021
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If you are really worried about this, and if you have the latest version of 3DMark available to you, there's a PCI-E bandwidth benchmark in there for precisely this purpose.
 

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