Motherboard Ram Channel B not working?

[Bulma]

I got a Gigabyte B450M DS3H about two years ago, and set it up with an AMD processor and two modules of 4GB RAM. According to the manual, the modules should be placed in slots 1 and 2, or 3 and 4.
(manual screenshot --> https://drive.google.com/file/d/17VVSRiVJa27aVV5a0Ek2vskYuPDe2BU0/view?usp=sharing )

(How it should be --> https://drive.google.com/file/d/1DPkLvCNb8YoTbxHn_mrp9-eLlC_7-tzP/view?usp=sharing )

That however didn't work, the PC wouldn't boot, so I tried all the slots and ended up using 4 and 2, which is channel A.

(What actually works --> https://drive.google.com/file/d/10M7TS0C8CSW8CtshTRwT67C-FYKqS5_Z/view?usp=sharing )
 
I thought it was probably me, that there was something I didn't understand right, so I let it slide.
Recently I bought two more modules 4 GB each, same as the others, but when I placed them all, the computer doesn't boot. I did more tests with two modules, new ones, old ones, in combination, I updated the bios, I reset the bios by removing the battery, nothing fixed the problem. It seems that Channel B does not work.
What should I do in this situation?

[dmdilks]

I just had something like this just happen to my son. The computer was running great for two months. Then it started to do the BSOD. Pull the memory and put in new memory it booted and ran for little bit. Then again the BSOD.

Pull the memory out slot 1. The computer would run all day no problems. Put the memory back in slot 1 BSOD. Put the memory in just like you have it the computer again would run all day.

I thought the memory channels were bad. AS I was working with support I had order another board the same one I was working with. Support setup a RMA on the board. Ship the board to them and started up the new board.

You ready for this the new board did the same thing. I said to myself this can't be the board. I did have another AMD board tried that one and got the same thing. Pull the CPU no bent pins and even clean it.

Put it back in and the same thing. I have been using AMD CPU's from day 1. This is the 1st one that went bad on me in over 25 yrs. So if you have another AMD board test the CPU in it. The CPU I was using is a Ryzen 5 3600.

That channel in the CPU could be bad. I'm not saying that could be it. But you better test everything before you start doing RMA's or buying new parts.

[dmdilks]

Plus if it is the CPU and it is still warranty. They are great I started the support on 2/3/21. I'll have my replacement on 2/12/21. They setup the RMA and even sent me a shipping Label.