ASRock Forums : X570 pro 4 - GPU in slot 3£

X570 pro 4 - GPU in slot 3£ : Thanks, appreciate the info!

Sun, 26 Feb 2023 11:55:07 +0000

Author: shootz
Subject: 25529
Posted: 26 Feb 2023 at 11:55am

Thanks, appreciate the info!

X570 pro 4 - GPU in slot 3£ : shootz wrote:So just to be...

Sun, 26 Feb 2023 11:52:06 +0000

Author: eccential
Subject: 25529
Posted: 26 Feb 2023 at 11:52am

shootz wrote:

So just to be clear, even with no GPU in slot 1, slot 3 will always be 4 lanes only, correct?

Correct. What you do with Slot1 has nothing to do with Slot3.
Slot1 is directly wired to CPU (16 lanes).
Slot3 is wired to chipset (4 lanes).

X570 pro 4 - GPU in slot 3£ : Thanks, and that's what I...

Sun, 26 Feb 2023 11:37:31 +0000

Author: shootz
Subject: 25529
Posted: 26 Feb 2023 at 11:37am

Thanks, and that's what I was a afraid of, only having 4 lanes in pcie slot 3.

So just to be clear, even with no GPU in slot 1, slot 3 will always be 4 lanes only, correct?

That means I will need a new Mobo to use the GPU, and the upgrade will have to wait a while.

X570 pro 4 - GPU in slot 3£ : Based on what I know about how...

Sun, 26 Feb 2023 11:05:03 +0000

Author: eccential
Subject: 25529
Posted: 26 Feb 2023 at 11:05am

Based on what I know about how the CPU itself works, and the various configurations listed in the manual, I believe this is how they're wired:

For this example, I'm using Matisse & Vermeer (same IO-Die) CPUs, with total of 24 PCIe Gen.4 lanes.

4 of them are used to connect to the chipset.
So 20 lanes are available for direct connection.

16x goes to PCIe Slot1.
4x goes to M2_1.

That's it! We're now out of direct-to-CPU lanes!

So PCIe Slot3 is from the chipset, and is only 4 lanes. I'm certain that the motherboard will only have 4 lanes worth of traces, because, why waste traces that won't even connect to anything?

M2_3 as well as PCIe Slots2/4 are also from the chipset.

Putting a high performance GPU in PCIe Slot3 means you're incurring additional latencies (data is all going through the chipset), but far worse problem is that it will only get 4 lanes worth of bandwidth. In fact, it's actually less than that, because CPU<->Chipset is only 4 lanes, and those are used for many other things (PCIe Slots2/4, M2_3, and other chipset functions like additional USB ports).

Edited by eccential - 26 Feb 2023 at 11:23am

X570 pro 4 - GPU in slot 3£ : I have an ASRock x570 pro 4 and...

Sun, 26 Feb 2023 09:28:50 +0000

Author: shootz
Subject: 25529
Posted: 26 Feb 2023 at 9:28am

I have an ASRock x570 pro 4 and currently use PCIE slot 1 for the GPU (rtx 2080). I was thinking of upgrading to a rtx 4070ti and it doesn't look like it will fit in slot 1 because it is too tall.

According to the manual, pcie slot 3 is x4 and not x16. I don't want to lose any performance by running it in an x4 slot.

I will not be using 2 GPUs but I was hoping to could install a GPU in slot 3.

Can anyone verify this is correct? Or is there any way to change it in the BIOS to swap which slot is x16?

From the website:
Slots
AMD Ryzen series CPUs (Vermeer, Matisse)
- 2 x PCI Express 4.0 x16 Slots (PCIE1/PCIE3: single at x16 (PCIE1); dual at x16 (PCIE1) / x4 (PCIE3))*
AMD Ryzen series CPUs (Cezanne, Renoir, Pinnacle Ridge)
- 2 x PCI Express 3.0 x16 Slots (PCIE1/PCIE3: single at x16 (PCIE1); dual at x16 (PCIE1) / x4 (PCIE3))*
AMD Ryzen series CPUs (Picasso)
- 2 x PCI Express 3.0 x16 Slots (PCIE1/PCIE3: single at x8 (PCIE1); dual at x8 (PCIE1) / x4 (PCIE3))*
- 2 x PCI Express 4.0 x1 Slots
- Supports AMD Quad CrossFireX??and CrossFireX??

https://www.asrock.com/mb/AMD/X570%20Pro4/index.asp#Specification