AMD Motherboards - Dual GPUs on B550M Pro4

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Dual GPUs on B550M Pro4 - default selection£

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=25174
Printed Date: 21 Mar 2025 at 2:08am
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com

Topic: Dual GPUs on B550M Pro4 - default selection£

Posted By: phofman
Subject: Dual GPUs on B550M Pro4 - default selection£
Date Posted: 07 Dec 2022 at 9:50pm

Hi,

Please is it possible to choose a default GPU to be used by Bios/win10 on boot on B550M Pro4 (Ryzen 9 5900X, no internal GPU)? A faster PCI-e v.4 graphics card would be used for headless rendering in Blender, while a slower PCI-e v.3 one would be for monitor output to avoid long refresh lockups.

Thanks a lot for any hints or help.

Replies:

Posted By: SerchTech
Date Posted: 08 Dec 2022 at 12:43am

Hi

I have no experience with B550M but observing the Pro4 one of your GPUs should be connected to the lower black x16 slot (Chipset) and will be limited at x4 PCIe lanes, seems perfect to connect your monitor.

Blender allow to users chose the GPU for Cycles in System Preferences so it is possible that you can work with your custom Dual-GPUs but I can't confirm it.

It would be great if BIOS or Windows allowed users to choose the main GPU but unfortunately (if I do not miss something) at this time it can not be done.

Good luck

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X399 Taichi (4.03)
Threadripper 2950X
DDR4 2 x HX432C16FB3K2/32

Posted By: phofman
Date Posted: 08 Dec 2022 at 2:26am

SerchTech wrote:

Hi

I have no experience with B550M but observing the Pro4 one of your GPUs should be connected to the lower black x16 slot (Chipset) and will be limited at x4 PCIe lanes, seems perfect to connect your monitor.

Thanks a lot. I tested with an old GTX1030 in the bottom slot. Windows eventually recognized the second GPU, Blender nicely distributes load between the two GPUs, clearly visible in the GPU performance charts of the windows task panel.

But BIOS does not seem to offer any way to pick the bottom GPU as default, to display POST, booting etc. I will have to leave that for the card in the top PCI-e v4 slot.

It would be great if BIOS or Windows allowed users to choose the main GPU but unfortunately (if I do not miss something) at this time it can not be done.

E.g. Linux would certainly allow chosing a GPU, maybe even windows, but BIOS is the culprit here. Not seeing a POST + boot loader is not viable.