X570M Pro4 - PCIe 4.0 x16 or PCIe 4.0 x4£
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=18642
Printed Date: 08 May 2024 at 12:15am
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: X570M Pro4 - PCIe 4.0 x16 or PCIe 4.0 x4£
Posted By: redneckbob
Subject: X570M Pro4 - PCIe 4.0 x16 or PCIe 4.0 x4£
Date Posted: 18 Apr 2021 at 12:35am
|
I purchased the X570M Pro4 and now I'm reading through the manual and I find that it doesn't match the marketing materials for this board. Ignoring the PCIe 4.0 x1 slot, I'm specifically asking about the number of PCIe 4.0 x16 slots. The marketing for the X570M Pro4 says: * 2 PCIe 4.0 x16 In the manual, it says: * PCIE1 (PCIe 4.0 x16 slot) is used for PCI Express x16 lane width graphics * PCIE3 (PCIe 4.0 x16 slot) is used for PCI Express x4 lane width graphics With the correct processor (AMD Ryzen 5 5600), are there two PCIe 4.0 x16 slots or one PCIe 4.0 x16 and one PCIe 4.0 x4? |
Replies:
Posted By: ket
Date Posted: 23 Apr 2021 at 1:07am
| The wording is a little muddied but what is meant is that the board has 2x full length PCI-E 16x slots. With multiple expansion slots populated the available bandwidth is then split between those devices, the Ryzen 5000 series provides 24 PCI-E 4.0 lanes and the X570 chipset provides up to 16 PCI-E 4.0 lanes. So for example; 16 lanes are utilised for graphics when the top PCI-E slot is poopulated and the remaining 24 lanes are divided between the other expansion, M.2 slots, and other devices. |
Posted By: Xaltar
Date Posted: 23 Apr 2021 at 1:43am
|
As Ket said, the wording is a bit erroneous. The slots are x16 for PCIe1 and x4 for PCIe3 though PCIe3 is physically an x16 slot (fits x16 cards) it is wired as x4. Bare in mind: PCIe 4.0 x4 = PCIe 3.0 x8 = PCIe 2.0 x16 bandwidth wise. Most GPUs will show no performance loss at PCIe 4.0 x4. I am fairly certain that where a handful might, this is due to optimization issues rather than bandwidth however. Even here though we are talking a handful of FPS out of 100+. PCIe3 is physically wired as an x4 slot as I said above, there is no situation in which it can operated higher. I thought I should clarify. ------------- 
|
Posted By: ket
Date Posted: 23 Apr 2021 at 2:22am
| ^^Exactly this. A modern midrange GPU will happily run even at PCI-E 4.0 8x and you won't lose a drop of performance, even at PCI-E 4x the performance hit will be negligible to none. Only the most powerful GPUs of today (RTX3080/90, 6800/6900XT) you will see some performance hit once you drop down to 4x speeds. |
Posted By: Xaltar
Date Posted: 23 Apr 2021 at 7:01am
|
Indeed and if you run at a resolution higher than 1080p there won't be a hit at all. -------------
|
Posted By: ket
Date Posted: 23 Apr 2021 at 7:37pm
| Yep, CPU bottleneck shifts to simply how much sheer GPU grunt you have above 1080p. I was doing some testing on that a little while ago with a 6800XT and 2700X @ 4.1GHz with optimised memory timings, I then did the same thing with a 3700X @ 4.1GHz and optimised memory timings. The jump was quite surprising newer generations of Zen at CPU limited resolutions with high end GPUs makes quite a difference, orders of magnitude more than PCI-E bandwidth. |