10Gbps NIC slow - Need help figuring out PCIe lane allocation

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jasonp153502d5

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Part TypePart NamePCI-E Configuration
MotherboardMSI MAG X670E Carbon Wi-Fi (BIOS Version 7D70v1C)N/A
CPUAMD R7 7800X3D24 PCI-E Lanes Total
Graphics CardPCI_E1: Powercolor Hellhound Radeon 7900XTPCIe 4.0 x16
NVME StorageM2_1: WD_BLACK SN850X 4TBPCIe 4.0 x4
NVME StorageM2_2: WD_BLACK SN850X 4TBPCIe 4.0 x4
Network CardPCI_E3: Intel X520-DA2 82599ES 10-Gigabit SFI/SFP+ NICPCIe 2.0 x1 (5.0 GT/s)

Motherboard Manual
Network Card Specifications
Network Switch Details

I just built a new PC for the first time in 12 years, and I'm pretty excited. Mostly I was able to get everything working, but I noticed my network speed is a bit slow.

I'm using an older 10Gbps SFP+ NIC connected to a 10Gbps USW-Aggregation switch. I have other servers plugged this switch via Direct Attached Copper (DAC) connectors.
I know this card is good, as it was in my old PC and was able to get 6Gbps throughput (still not great).
With the new PC, I'm only getting 3Gbps:
Screenshot from 2024-01-16 19-03-09.png


When I look closer at the PCI slots, I can see the network card is being "downgraded" to 1x speed:
Screenshot from 2024-01-16 19-08-08.png


I think the problem is I'm running out of PCI-E lanes?
Can anyone help me understand how many lanes I need for this hardware, and if I can downgrade some of them without losing performance?
My best guess in the table above.

Thanks!
 
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3x PCI-E x16 slot (Qty)
Supports x16/x0/x4, x8/x8/x4
PCI_E1 Gen PCIe 5.0 supports up to x16 (From CPU)
PCI_E2 Gen PCIe 5.0 supports up to x8 (From CPU)
PCI_E3 Gen PCIe 4.0 supports up to x4 (From Chipset)
Click to expand...

Your ancient network card is PCIe 2.0.
PCIe 2.0 speed in a 16x slot is up to 8 GB/s.
PCIe 2.0 speed in a 4x slot is up to 2 GB/s, and PCIe 4.0 speed 1x has the same speed.
I think you won't get any faster speed with a PCIe 2.0 device in this slot.
 
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So it's basically the same problem as in this thread.

The X520 can do 10 Gbps at PCIe 2.0 x4 no problem.
Keep in mind the card is rated for 10Gbps, not 10GB/s.
The conversion is: 10 Gbps to GB/s = 1.25 GB/s

The PCI_E3 slot should run at x4 to the chipset.
The problem is I'm getting downgraded to x1 and I don't know why.
 
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jasonp153502d5 said:
The problem is I'm getting downgraded to x1 and I don't know why.
Click to expand...
Yes, I see the issue .... The E3 slot has its PCIe functionality from the chipset and should always have 4 lanes available.
There's a way to check if this is a PCIe 4.0/2.0 conversion issue.
Just swap your devices in PCIe_E2 and PCIe_E3. If your NVME SSD gets more than 1 lane in E3, then it is a PCIe 2.0 conversion issue. If your NVME also gets 1 single lane in E3, it's something with the board.
Good luck!
 
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Sorry can you clarify what to swap? PCI_E1 is my video card, and I think it's too big to plug anything in slot PCI_E2.
Are you saying to swap around my NVME disks in M2_x ?
 
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