ram slots a1 b1 not working

I have a problem, I have 4 RAM sticks that do not work together I have RAM: 2x16 GB + 2x16 GB, they are working and work separately and in pairs, but only in slots A2 B2. When I insert one or two sticks, for example, into slot A1 or B1 and connect the PC to the power supply, even without...