centrals

I’ve tried the other 2 and nothing, I’ve read about A1/A2 slots not working and only the B1/B2 slots work.

I’ve looked absolutely everywhere on how to fix this and I got nothing. I’ve cleared the CMOS several of times and have tested each individual DIMM slot, but only B1/B2 worked (with a single stick). For a second I had 2 sticks within B1/B2 at the same time, and was recommended to reseat the CPU, after reseating now only one sticks works, and B1 won’t even boot with one stick in it. I’ve checked and made sure that there was no bent pins on the CPU socket and have used dual channel on a different mobo with the same CPU and RAM. BTW, this is a used mobo that I purchased a couple days ago and has no defects/bent CPU pins. Any help would be appreciated as i’m in shambles over this. SPECS: i5-6600k AMD RX480 2/8gb SK Hynix RAM (Are capable of dual channel I checked mobo manual) 500W EVGA PSU