How to figure out in AMD what usb port is connected to cpu.

[daviddave1]

with the help of USB Device Tree Viewer and hwinfo you should find out what usb port is straight connected to the amd processor. There was a guide somewhere here? I cant find it. Can someone help? I have an Asrock asrock b850i lightning wifi and an 9850x3d.

[RealNC]

Usually the manual of the mainboard has that info.

[daviddave1]

No i remember its pretty hard to find out. Hope someone can help.

[Cosmostraveler]

No i remember its pretty hard to find out. Hope someone can help.

U can find this out via HWInfo, u can either install it or use a portable version, the app has various uses.



In case the image doesn't load for some reason, u can find the link https://imgur.com/a/CnfWyXm here

[RealNC]

No i remember its pretty hard to find out. Hope someone can help.

I just looked at the user manual:

https://download.asrock.com/Manual/B850 ... 20WiFi.pdf

On page 3, it says:

CPU:
• 1 x USB 3.2 Gen2 Type-C (Rear)
• 2 x USB 3.2 Gen2 Type-A (Rear)

Chipset:
• 1 x USB 3.2 Gen1 Type-C (Front)
• 3 x USB 3.2 Gen1 Type-A (1 Rear, 2 Front)
• 6 x USB 2.0 (4 Rear, 2 Front)

So all the USB 2 ports are from the chipset. The USB 3 Gen1 ports are also all from the chipset. The USB3 Gen2 ports are from the CPU. Then you just look at the rear panel diagram and it's clear which ones are USB Gen2, making them the only CPU-provided ports:

Screenshot_20260802_235206.png (84.83 KiB) Viewed 362 times

The CPU ports are ports 3, 11 and 12.

I don't think this was very difficult

[daviddave1]

No i remember its pretty hard to find out. Hope someone can help.

U can find this out via HWInfo, u can either install it or use a portable version, the app has various uses.



In case the image doesn't load for some reason, u can find the link https://imgur.com/a/CnfWyXm here

hey tnx for the reply! this is what i got https://imgur.com/a/etNbJNj


CHATGPT tells me the following: Yes, partially.

Based on this AIDA64 PCI bus tree, you can already make a reasonable assessment.

Here's what I see:

AMD Raphael – Root Complex = the CPU.
Under it, there are several PCIe GPP Bridges, which belong to the CPU's PCIe lanes.
Your USB controllers (AMD Raphael – USB 3.1 Controller 0 and Controller 1) are listed under AMD Raphael, which suggests they are CPU-integrated USB controllers.
At the bottom, you can see AMD Promontory 21L FCH. Everything listed under that is routed through the chipset.

So, based on your screenshot:

Directly connected to the CPU

AMD Raphael – USB 3.1 Controller 0
AMD Raphael – USB 3.1 Controller 1
AMD Zen – Audio Processor / HD Audio Controller
AMD Zen – Cryptographic Coprocessor (PSP/CCP)
AMD Raphael – Data Fabric Functions

Connected through the chipset

AMD Promontory 21L FCH – SMBus and ACPI Controller
AMD Promontory/Bixby FCH – LPC Bridge
Everything listed under the Promontory/FCH.

However...

Your screenshot does not show which physical rear USB ports belong to USB Controller 0 or Controller 1. To determine that, you'll need either:

USBTreeView (the best option), or
the motherboard manual/block diagram.

That will let you identify exactly:

which rear USB port is connected to which controller;
which ports are CPU-direct and which are routed through the chipset.

This is especially useful if you want to connect your mouse or keyboard to a CPU-direct USB port for the lowest possible latency.

------------

Looks like the 3.1 controller is the one directly to the cpu? Did noot expect that. Gonna look into it further!

[daviddave1]

No i remember its pretty hard to find out. Hope someone can help.

I just looked at the user manual:

https://download.asrock.com/Manual/B850 ... 20WiFi.pdf

On page 3, it says:

CPU:
• 1 x USB 3.2 Gen2 Type-C (Rear)
• 2 x USB 3.2 Gen2 Type-A (Rear)

Chipset:
• 1 x USB 3.2 Gen1 Type-C (Front)
• 3 x USB 3.2 Gen1 Type-A (1 Rear, 2 Front)
• 6 x USB 2.0 (4 Rear, 2 Front)

So all the USB 2 ports are from the chipset. The USB 3 Gen1 ports are also all from the chipset. The USB3 Gen2 ports are from the CPU. Then you just look at the rear panel diagram and it's clear which ones are USB Gen2, making them the only CPU-provided ports:


Screenshot_20260802_235206.png


The CPU ports are ports 3, 11 and 12.

I don't think this was very difficult

ty so much! you solved it and helped me out a loth! I am tingering with my new build all day! I could not see the forest cause of all the trees!! PS so its nr 3 USB 3.2 Gen2 Type-A Port (USB32_2)** and nr 11 USB 3.2 Gen2 Type-A Port (USB32_1) right? EDIT you already conformed this! NICE!! TNX AGAIN!!!

[RealNC]

ty so much! you solved it and helped me out a loth! I am tingering with my new build all day! I could not see the forest cause of all the trees!! PS so its nr 3 USB 3.2 Gen2 Type-A Port (USB32_2)** and nr 11 USB 3.2 Gen2 Type-A Port (USB32_1) right?

Yes. The two ports next to the ethernet port are from the CPU, and the one port right next to the HDMI port (so the middle one) is also from the CPU. All the others are from the chipset.

[daviddave1]

tnx i just see now u already confirmed it before! tnx for the double conformation!

[vnb]

ASRock and MSI have always been user friendly in they way that they provide their block diagram inside the manual so you can easily check for things like which USB is connected to the CPU, PROM 21 chipset, or even a hub. Or even the way the components are internally wired. That’s something i always appreciated from them.

On the other hand Gigabyte only provide this for their high end mobos and ASUS, well typically in ASUS fashion they do not.
You have to beg for it via their customer support and pray the agent exchanging with you is in a good mood to provide you with what you have asked for.

U can find this out via HWInfo, u can either install it or use a portable version, the app has various uses.


In case the image doesn't load for some reason, u can find the link https://imgur.com/a/CnfWyXm here

Great recommendation! however USB Device Tree Viewer (uncheck show child devices) is clearer than hwinfo imo.