X570 pro 4 - GPU in slot 3£
Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=25529
Printed Date: 01 Aug 2025 at 5:08am
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Topic: X570 pro 4 - GPU in slot 3£
Posted By: shootz
Subject: X570 pro 4 - GPU in slot 3£
Date Posted: 26 Feb 2023 at 9:28am
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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" rel="nofollow - https://www.asrock.com/mb/AMD/X570%20Pro4/index.asp#Specification |
Replies:
Posted By: eccential
Date Posted: 26 Feb 2023 at 11:05am
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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). |
Posted By: shootz
Date Posted: 26 Feb 2023 at 11:37am
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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. |
Posted By: eccential
Date Posted: 26 Feb 2023 at 11:52am
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). |
shootz wrote:Posted By: shootz
Date Posted: 26 Feb 2023 at 11:55am
| Thanks, appreciate the info! |