Question Asus Crosshair VIII Formula: GPU blocks PCIE x1 slot, can I put my sound card in another x16 w/out performance issues?

[Architekt]

Current set up:
* Asus ROG Crosshair VIII Formula mobo
* Aorus RTX 3090 video card
* AMD 5950x CPU (on the way, won't be here for like a week so I can't test the answer to my question)
* Sound blaster Z PCIe x1 internal sound card
* two M.2 cards in the PCIe 4.0 slots

The 3090 is ginormous. It totally blocks the PCIe x1 slot as well as the next PCIe x16 slot. There's not even enough space to try to attempt to fit a riser cable in there. Anyway, the 3rd, bottom PCIe x16 slot is open. I know that I can put the sound card which is x1 into the slot, but my question is, will that then make the 3090 run at x8 instead of x16? The manual is confusing on this. Here's all it says, which doesn't give me an indication about what happens if a non graphics card is in the 3rd slot with nothing in the 2nd.

 

[Leeea]

I am not sure.

But even if it does slow it down, it is unlikely you will ever notice the difference.

 

[UsandThem]

I have two different cards (Creative AE-5 and TP Link wifi card) in two PCIe 2.0 x1 slots, and a video card in the top PCIe 3.0 x16 slot, and my GPU runs at full speed. I don't think your motherboard would be any different from the specs listed on Asus' website.

 

[KentState]

Let me test it out today as I have the same motherboard and 3090. I will just use a PCIE network card instead. It also have 2x PCIE 4 NVMe drives so it should be close enough.

 

[KentState]

I tested this with a Chelsio 10Gbe network card which is PCIE 3.0 x8. The card appears to be running at x16 4.0 and the network card is showing 8GT/s.

 

[thigobr]

That's expected.
The third slot is connected to the X570 chipset with 4 lanes PCIE4.0.
X570 chipset itself is connected to the CPU by a dedicated 4 lanes (also PCIE4.0 when using Ryzen 3000/5000 CPUs).
PCIE_1 and PCIE_2 are connected to the CPU and they will split lanes 8x/8x if both are occupied.

The diagram is not specifically for your Asus Crosshair but the allocation is the same:

 

[HomerJS]

Question for those in this thread. I see installed discrete network and sounds cards. Wondering about rationale.

Mobo sound quality?
Network/audio traffic overhead?

I had written off those kinds of discrete cards but maybe reconsider?? It's been 6-7 years since I purchased components.

 

[HomerJS]

I tested this with a Chelsio 10Gbe network card which is PCIE 3.0 x8. The card appears to be running at x16 4.0 and the network card is showing 8GT/s.

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Drool

 

[KentState]

For me, I have 10Gbe home networking and I have found that the Chelsio cards are of extremely high quality so I trust them over Aquantia. They are used in the enterprise so their off loading implementations for example actually work. I have found that, at least on my network, Aquantia cards have horrible connectivity issues unless I disable a lot of the features.