USB Keyboard & Mouse get instantly disabled with 2dGPUs installed

Issues & Assistance
1

Hello,

I have been trying to switch to CachyOS for some days now but cant get it to work while having both of my dGPUs (4080S & 5060) installed in my PC. Everything works fine as long as my second dGPU (5060) isn’t installed but as soon as i install it and start booting into CachyOs my Keyboard & Mouse become unusable (I think they have no power / no signal) (re-plugging or switching USB port didn’t help).

This is what happens with my 5060 installed:

Start PC (with 5060 installed) → boot into rEFInd → Choose CachyOS → CachyOS boots → almost immediately RGB Turns off on Mouse / Keyboard → CachyOS starts onto Login Screen but i´m Unable to do anything because my Mouse & Keyboard wont work.

I´ve read about aggressive power saving maybe causing it but since it works just fine with my 4080S installed i´m not sure about that being the case here… And since i am very much new to Linux i feel like i´m not making much progress in troubleshooting it myself since this post here…

Any help with this or even a few tips to troubleshooting would be much appreciated.

My PC specs: (maybe they help)

CPU: Ryzen 9 9950X3D

Mainboard: MSI MAG X870E Tomahawk Wifi (Bios version: 7E59v2AB)

RAM: 32GB 6000mt/s CL30 PVV532G600C30K

IGPU: Disabled

GPU1: ASUS 4080 Super ProArt

GPU2: Zotac 5060 Solo

Storage:

Samsung 970 Evo Plus 500Gb

Samsung 970 Evo Plus 2TB

Viper VP4100 1TB

SanDisk SDSSDH3 2TB

Crucial MX500 2TB

edit 1:

PSU: Seasonic Prime TX-1600 Noctua Edition (1600W)

CachyOS is installed on the “Samsung 970 Evo Plus 2TB” listed above and i have Windows 11 installed on the Samsung “970 Evo Plus 500GB” thats listed above. In Windows 11 i dont have any Problems with my Second GPU.

2

Sounds like you need a bigger Power Supply to handle both GPUs.

3

Hi thanks for the reply,

unfortunately I don’t think that’s it, since i have a Seasonic Prime TX-1600 Noctua Edition PSU…

also i dont have any Problems in Windows with the 2 Gpus…

Any idea how i could check if its the PSU´s fault?

4

Are your KB&M connected directly to the PC or via a hub built into a monitor?

5

Hi thanks for the reply,

my KB&M are connected to the Backpanel of my MB. They are using the USB-A 5Gbps ports.

6

Have you tried different USB Ports?

Check the block diagram of your mainboard, it could be that the PCIe slot you’re putting the 2nd dGPU in is sharing bandwidth with that particular USB port.

7

Hi after some more trying around i found out that only the cpu bound Usb ports work… But still every other port does not… also no video from my other gpu…

It seems like everything that is connected via Chipset doesnt work with the 2nd dgpu installed.

I come to say that since the drives, network and everything else thats connected via Chipset doesnt work.

But since i can use my M&KB now i can run dmesg:

IMG_20260517_152916383
IMG_20260517_1529163831920×1080 646 KB

These are the errors i got but to be honest i cant interpret them very well…