Dual channel not working after buying a new processor

Hello everyone, I recently changed my old athlone 635 to a hair dryer ii x4 955t. Plugged it into the motherboard and the computer didn't start. I checked everything, and realized that the computer does not start if there are 2 RAM sticks in the motherboard. It's not about the slats, they are all fully functional. Decided to put the old percent. I put it on, turn it on and again it does not start with 2 bars. When I installed it, I didn't seem to break anything. The board starts only when there are 2 bars at the same time, and it does not matter in which slot. Cleaned the contacts. In general, does anyone know what could be such that I do not start?
Motherboard: ASRock N68CS-UCC
Planks: 2 ddr3 Samsung.