x870 Tomahawk sometimes boots 5090 at PCIe 3.0 instead of 5.0

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eberenzjess15a702e5

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Sort of a weird issue. I have the x870 Tomahawk on the 7E51v1A3 bios from 2025-03-05. I have the ASUS TUF 5090 (non-OC) plugged into the top-most PCIe slot.

Most of the time, GPU-Z says the card is running at PCIe x16 5.0 @ x16 5.0. However, sometimes after booting, it says it's running at PCIe x16 5.0 @ x16 3.0.

My BIOs have it set to "auto" as I couldn't find a way to force PCIe 5.0.

Sorry for the poor quality images.
 

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eberenzjess15a702e5 said:
Sort of a weird issue. I have the x870 Tomahawk on the 7E51v1A3 bios from 2025-03-05. I have the ASUS TUF 5090 (non-OC) plugged into the top-most PCIe slot.

Most of the time, GPU-Z says the card is running at PCIe x16 5.0 @ x16 5.0. However, sometimes after booting, it says it's running at PCIe x16 5.0 @ x16 3.0.

My BIOs have it set to "auto" as I couldn't find a way to force PCIe 5.0.

Sorry for the poor quality images.
Click to expand...
eberenzjess15a702e5 said:
Sort of a weird issue. I have the x870 Tomahawk on the 7E51v1A3 bios from 2025-03-05. I have the ASUS TUF 5090 (non-OC) plugged into the top-most PCIe slot.

Most of the time, GPU-Z says the card is running at PCIe x16 5.0 @ x16 5.0. However, sometimes after booting, it says it's running at PCIe x16 5.0 @ x16 3.0.

My BIOs have it set to "auto" as I couldn't find a way to force PCIe 5.0.

Sorry for the poor quality images.
Click to expand...
Click the “?” icon next to Bus Interface and run the render test.
Did the speed switch to PCIe 5.0?
 
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eberenzjess15a702e5 said:
Sort of a weird issue. I have the x870 Tomahawk on the 7E51v1A3 bios from 2025-03-05. I have the ASUS TUF 5090 (non-OC) plugged into the top-most PCIe slot.

Most of the time, GPU-Z says the card is running at PCIe x16 5.0 @ x16 5.0. However, sometimes after booting, it says it's running at PCIe x16 5.0 @ x16 3.0.

My BIOs have it set to "auto" as I couldn't find a way to force PCIe 5.0.

Sorry for the poor quality images.
Click to expand...
If it ramps up to PCIe 5.0, then everything’s fine. But if you get stuttering or freezing, you’ll need to manually set the slot to Gen 4 in BIOS.

I had a similar issue with a 5080 Astral—freezes and stuck at PCIe 1.1—but a BIOS update may have fixed it.
Also, GPU-Z shows the current interface speed, so to verify if PCIe 5.0 isn’t working, you need to start the render test.

What worked for me was switching the GPU to an MSI card.
Interestingly, my MSI Vanguard wouldn’t run at Gen5 on my friend’s X870E Hero, but it works perfectly on my setup.

This shows the issue likely lies in either the VBIOS or the motherboard BIOS.
In my experience, a GPU and motherboard from the same brand work best together at full speeds.
 
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