Can someone help me solve opencl problem,thanks!

I have 2 powercolor dragon rx 470(4G) and 1 powercolor devil rx 470(4G).
I install step by step by this

But it can recognize my GPU

And clinfo does not show them

How should solve this problem?
thanks!!!

(lspci | grep)

I had at the beginning a problem like this one.

In my case it was not a big problem, but a long problem to find.

Short Version: If you use riser-card, check them ... check the USB-Connection and check the Risercards.

Do you try to install a Test-Windows-System (maybe on a second hdd) and find Windows your Cards? Windows had a lot lesser troubles with GPUs

BTW: On Ubuntu i like the small software "inxi" for hardwareinformations ...
"inxi -G" should show all GPUs

Thanks for you help!

Yes,I'm use riser-card, I would check them immediately.
But it is the problems of riser card's connection or just the riser?

I would try to install Test-Windows-System to check this problem, thanks for your information!

Haha, I has learn it, thanks!

I has some questions,before I added the third card(devil rx 470), they can run normally.
But after I added devil rx 470, it started have this problem.

And then I remove one of them (use only devil and dragon or two original dragon cards )
it could both work normally.......
I was puzzled by this.....