Why can't the PC start after adding a second RAM stick?

Question

RAM

Good afternoon. I bought a second chip of RAM, the volume / randomizer / voltage is the same with the first chip. The only thing - on the first 2400 GHz, on the second 2666 GHz. When I start the PC, the screen does not turn on. Checked individual dice - work. All slots also work. What is the problem, I can not understand. Motherboard - Asus prime b450m-k

Answer 1

You just need to buy both 2666GHz sticks, or buy one 2400GHz one. And in no case is it possible to combine two different purity, it does not work that way)

Answer 2

Conflict with each other, it happens. Maybe, when manually setting the frequencies and timings in the BIOS, they will work together, or maybe not.