NO POST ROG Strix B450-F with AMD Athlon 3000g

[kingpen79777]

I started this build with a used ROG Strix B450-F that has worked flawlessly for several months now. I chose a new Athlon 3000G for my CPU/GPU because of the current issues getting a gpu and it was affordable and in stock. 

I have one stick of 8gb V-color ram (yes I know boooo single channel I'm cheap for now because it should work)  PSU is a new Power Flower 850w gold again because cheap and in stock. main boot drive is WD 1T HDD (yeah I'm saving for a SSD)

the main purpose of this set up has become test bench for random hardware and oddball repairs. this set has performed great until I swapped in a new to me 5500xt 8gb and booted up the system. I hadn't even connected the HDMI to the GPU I was still running of the CPU and onboard graphics. just wanted to see if the used card would boot.  it fails to POST, I get the LED to flash yellow (DRAM) red (CPU) then Yellow and then red again then nothing. the fans all spin the RGB is all on the hard drive is spinning but nothing for video output or continuation of post. this has been a working test bench for months I tried that card in another computer and it works fine so I'm not thinking it was the GPUs fault. 

 

I have tried: 

Known good ram from another computer still no change

swapping cables the HDMI and all PCIe And CPU cables (don't have a 24pin laying around extra or I would've swapped that too) 

I swapped the GPU into all the slots and tried video output from the card incase it was defaulting to that still nothing. 

I have reset the CMOS multiple times trying to get it to boot (yes when I boot it back up its without a GPU so that the CPU and onboard graphics pic up instead)

 

still nothing 

I'm worried I have a dead MB or CPU 

beyond frustrated at this point I would hate to have fried a CPU during a shortage. 

[kingpen79777]

sorry this is my first time on the forum  I don't use forums much but I'm at my wits end and cant find anything online directly solving my issue. 

[kingpen79777]

figures....